LCOV - code coverage report
Current view: top level - src/motion - bfgs_optimizer.F (source / functions) Coverage Total Hit
Test: CP2K Regtests (git:123285f) Lines: 89.4 % 762 681
Test Date: 2026-11-04 00:58:17 Functions: 100.0 % 20 20

            Line data    Source code
       1              : !--------------------------------------------------------------------------------------------------!
       2              : !   CP2K: A general program to perform molecular dynamics simulations                              !
       3              : !   Copyright 2000-2026 CP2K developers group <https://cp2k.org>                                   !
       4              : !                                                                                                  !
       5              : !   SPDX-License-Identifier: GPL-2.0-or-later                                                      !
       6              : !--------------------------------------------------------------------------------------------------!
       7              : 
       8              : ! **************************************************************************************************
       9              : !> \brief Routines for Geometry optimization using BFGS algorithm
      10              : !> \par History
      11              : !>      Module modified by Pierre-André Cazade [pcazade] 01.2020 - University of Limerick.
      12              : !>      Modifications enable Space Group Symmetry.
      13              : ! **************************************************************************************************
      14              : MODULE bfgs_optimizer
      15              : 
      16              :    USE atomic_kind_list_types,          ONLY: atomic_kind_list_type
      17              :    USE atomic_kind_types,               ONLY: get_atomic_kind,&
      18              :                                               get_atomic_kind_set
      19              :    USE bibliography,                    ONLY: Lindh1995,&
      20              :                                               cite_reference
      21              :    USE cell_types,                      ONLY: cell_type,&
      22              :                                               pbc
      23              :    USE constraint_fxd,                  ONLY: fix_atom_control
      24              :    USE cp_blacs_env,                    ONLY: cp_blacs_env_create,&
      25              :                                               cp_blacs_env_release,&
      26              :                                               cp_blacs_env_type
      27              :    USE cp_external_control,             ONLY: external_control
      28              :    USE cp_files,                        ONLY: close_file,&
      29              :                                               open_file
      30              :    USE cp_fm_basic_linalg,              ONLY: cp_fm_column_scale,&
      31              :                                               cp_fm_matvec,&
      32              :                                               cp_fm_transpose
      33              :    USE cp_fm_diag,                      ONLY: choose_eigv_solver
      34              :    USE cp_fm_struct,                    ONLY: cp_fm_struct_create,&
      35              :                                               cp_fm_struct_release,&
      36              :                                               cp_fm_struct_type
      37              :    USE cp_fm_types,                     ONLY: cp_fm_create,&
      38              :                                               cp_fm_get_info,&
      39              :                                               cp_fm_read_unformatted,&
      40              :                                               cp_fm_release,&
      41              :                                               cp_fm_set_all,&
      42              :                                               cp_fm_to_fm,&
      43              :                                               cp_fm_type,&
      44              :                                               cp_fm_write_unformatted
      45              :    USE cp_log_handling,                 ONLY: cp_get_default_logger,&
      46              :                                               cp_logger_type,&
      47              :                                               cp_to_string
      48              :    USE cp_output_handling,              ONLY: cp_iterate,&
      49              :                                               cp_p_file,&
      50              :                                               cp_print_key_finished_output,&
      51              :                                               cp_print_key_should_output,&
      52              :                                               cp_print_key_unit_nr
      53              :    USE cp_subsys_types,                 ONLY: cp_subsys_get,&
      54              :                                               cp_subsys_type
      55              :    USE force_env_types,                 ONLY: force_env_get,&
      56              :                                               force_env_type
      57              :    USE global_types,                    ONLY: global_environment_type
      58              :    USE gopt_f_methods,                  ONLY: &
      59              :         cp_eval_at, gopt_f_ii, gopt_f_io, gopt_f_io_finalize, gopt_f_io_init, &
      60              :         gopt_f_project_coord, gopt_f_project_step, gopt_f_project_vector, gopt_f_space_group_init, &
      61              :         gopt_f_space_group_show, print_geo_opt_header, print_geo_opt_nc
      62              :    USE gopt_f_types,                    ONLY: gopt_f_type
      63              :    USE gopt_param_types,                ONLY: gopt_param_type
      64              :    USE ieee_arithmetic,                 ONLY: ieee_is_finite
      65              :    USE input_constants,                 ONLY: bfgs_direct,&
      66              :                                               bfgs_inverse,&
      67              :                                               default_cell_method_id,&
      68              :                                               default_ts_method_id
      69              :    USE input_section_types,             ONLY: section_vals_get_subs_vals,&
      70              :                                               section_vals_type,&
      71              :                                               section_vals_val_get,&
      72              :                                               section_vals_val_set
      73              :    USE iso_fortran_env,                 ONLY: iostat_end
      74              :    USE kinds,                           ONLY: default_path_length,&
      75              :                                               dp
      76              :    USE machine,                         ONLY: m_flush,&
      77              :                                               m_walltime
      78              :    USE mathlib,                         ONLY: det_3x3,&
      79              :                                               inv_3x3
      80              :    USE message_passing,                 ONLY: mp_para_env_type
      81              :    USE parallel_gemm_api,               ONLY: parallel_gemm
      82              :    USE particle_list_types,             ONLY: particle_list_type
      83              : #include "../base/base_uses.f90"
      84              : 
      85              :    IMPLICIT NONE
      86              :    PRIVATE
      87              : 
      88              :    CHARACTER(len=*), PARAMETER, PRIVATE :: moduleN = 'bfgs_optimizer'
      89              :    ! Parameters of the Lindh 1995 model Hessian (atom rows H/C/O-N, pair
      90              :    ! columns). Screening constants for construct_initial_hess.
      91              :    REAL(KIND=dp), PARAMETER, PRIVATE :: lindh_alpha(3, 3) = &
      92              :                                         RESHAPE([1.0_dp, 0.3494_dp, 0.3494_dp, &
      93              :                                                  0.3949_dp, 0.2800_dp, 0.2800_dp, &
      94              :                                                  0.3949_dp, 0.2800_dp, 0.1800_dp], [3, 3])
      95              :    REAL(KIND=dp), PARAMETER, PRIVATE :: lindh_r0(3, 3) = &
      96              :                                         RESHAPE([1.35_dp, 2.10_dp, 2.53_dp, &
      97              :                                                  2.10_dp, 2.87_dp, 3.40_dp, &
      98              :                                                  2.53_dp, 3.40_dp, 3.40_dp], [3, 3])
      99              :    REAL(KIND=dp), PARAMETER, PRIVATE :: lindh_cutoff = 6.0_dp
     100              :    REAL(KIND=dp), PARAMETER, PRIVATE :: lindh_stretch_factor = 0.45_dp
     101              :    REAL(KIND=dp), PARAMETER, PRIVATE :: lindh_angle_factor = 0.15_dp
     102              :    REAL(KIND=dp), PARAMETER, PRIVATE :: lindh_denom_floor = 0.01_dp
     103              :    LOGICAL, PARAMETER                   :: debug_this_module = .TRUE.
     104              : 
     105              :    ! Both matrix representations share one restart format and the existing file name.
     106              :    CHARACTER(LEN=16), PARAMETER         :: bfgs_restart_magic = "CP2K BFGS STATE "
     107              :    INTEGER, PARAMETER                   :: bfgs_restart_version = 1
     108              :    REAL(KIND=dp), PARAMETER             :: min_hessian_eigenvalue = 1.0e-4_dp
     109              : 
     110              :    PUBLIC :: bfgs_read_restart_header, geoopt_bfgs
     111              : 
     112              : CONTAINS
     113              : 
     114              : ! **************************************************************************************************
     115              : !> \brief Main driver for BFGS geometry optimizations
     116              : !> \param force_env ...
     117              : !> \param gopt_param ...
     118              : !> \param globenv ...
     119              : !> \param geo_section ...
     120              : !> \param gopt_env ...
     121              : !> \param x0 ...
     122              : !> \par History
     123              : !>      01.2020 modified to perform Space Group Symmetry [pcazade]
     124              : ! **************************************************************************************************
     125          905 :    RECURSIVE SUBROUTINE geoopt_bfgs(force_env, gopt_param, globenv, geo_section, gopt_env, x0)
     126              : 
     127              :       TYPE(force_env_type), POINTER                      :: force_env
     128              :       TYPE(gopt_param_type), POINTER                     :: gopt_param
     129              :       TYPE(global_environment_type), POINTER             :: globenv
     130              :       TYPE(section_vals_type), POINTER                   :: geo_section
     131              :       TYPE(gopt_f_type), POINTER                         :: gopt_env
     132              :       REAL(KIND=dp), DIMENSION(:), POINTER               :: x0
     133              : 
     134              :       CHARACTER(len=*), PARAMETER                        :: routineN = 'geoopt_bfgs'
     135              :       REAL(KIND=dp), PARAMETER                           :: one = 1.0_dp, zero = 0.0_dp
     136              : 
     137              :       CHARACTER(LEN=5)                                   :: wildcard
     138              :       INTEGER                                            :: handle, info, iter_nr, its, &
     139              :                                                             matrix_method, maxiter, ndf, &
     140              :                                                             output_unit
     141              :       LOGICAL                                            :: conv, hesrest, hess_reset, inverse, &
     142              :                                                             shell_present, should_stop, &
     143              :                                                             use_mod_hes, use_rfo
     144              :       REAL(KIND=dp)                                      :: ediff, emin, eold, etot, pred, rad, rat, &
     145              :                                                             step, t_diff, t_now, t_old
     146          905 :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:)           :: dg, dr, dx, eigval, gold, work, xold
     147          905 :       REAL(KIND=dp), DIMENSION(:), POINTER               :: g
     148              :       TYPE(atomic_kind_list_type), POINTER               :: atomic_kinds
     149              :       TYPE(cp_blacs_env_type), POINTER                   :: blacs_env
     150              :       TYPE(cp_fm_struct_type), POINTER                   :: fm_struct_hes
     151              :       TYPE(cp_fm_type)                                   :: eigvec_mat, hess_mat, hess_tmp
     152              :       TYPE(cp_logger_type), POINTER                      :: logger
     153              :       TYPE(cp_subsys_type), POINTER                      :: subsys
     154              :       TYPE(mp_para_env_type), POINTER                    :: para_env
     155              :       TYPE(section_vals_type), POINTER                   :: print_key, root_section
     156              : 
     157          905 :       NULLIFY (logger, g, blacs_env)
     158         1810 :       logger => cp_get_default_logger()
     159          905 :       para_env => force_env%para_env
     160          905 :       root_section => force_env%root_section
     161          905 :       t_old = m_walltime()
     162              : 
     163          905 :       CALL timeset(routineN, handle)
     164          905 :       CALL section_vals_val_get(geo_section, "BFGS%TRUST_RADIUS", r_val=rad)
     165          905 :       print_key => section_vals_get_subs_vals(geo_section, "BFGS%RESTART")
     166          905 :       CALL section_vals_val_get(geo_section, "BFGS%METHOD", i_val=matrix_method)
     167          905 :       inverse = matrix_method == bfgs_inverse
     168          905 :       maxiter = gopt_param%max_iter
     169          905 :       conv = .FALSE.
     170          905 :       rat = 0.0_dp
     171          905 :       wildcard = " BFGS"
     172              : 
     173              :       ! Stop if not yet implemented
     174          905 :       SELECT CASE (gopt_env%type_id)
     175              :       CASE (default_ts_method_id)
     176          905 :          CPABORT("BFGS method not yet working with DIMER")
     177              :       END SELECT
     178              : 
     179          905 :       CALL section_vals_val_get(geo_section, "BFGS%USE_RAT_FUN_OPT", l_val=use_rfo)
     180          905 :       CALL section_vals_val_get(geo_section, "BFGS%USE_MODEL_HESSIAN", l_val=use_mod_hes)
     181          905 :       CALL section_vals_val_get(geo_section, "BFGS%RESTART_HESSIAN", l_val=hesrest)
     182          905 :       IF (inverse .AND. use_rfo) THEN
     183              :          CALL cp_abort(__LOCATION__, &
     184            0 :                        "BFGS METHOD INVERSE does not support USE_RAT_FUN_OPT")
     185              :       END IF
     186              :       IF (inverse) THEN
     187           10 :          IF (.NOT. ieee_is_finite(rad) .OR. rad <= 0.0_dp) THEN
     188              :             CALL cp_abort(__LOCATION__, &
     189            0 :                           "BFGS TRUST_RADIUS must be finite and positive")
     190              :          END IF
     191              :       END IF
     192              :       output_unit = cp_print_key_unit_nr(logger, geo_section, "PRINT%PROGRAM_RUN_INFO", &
     193          905 :                                          extension=".geoLog")
     194          905 :       IF (output_unit > 0) THEN
     195          476 :          IF (inverse) THEN
     196            5 :             WRITE (UNIT=output_unit, FMT="(/,T2,A)") "BFGS| Matrix update method: INVERSE"
     197              :          ELSE
     198          471 :             WRITE (UNIT=output_unit, FMT="(/,T2,A)") "BFGS| Matrix update method: DIRECT"
     199              :          END IF
     200          476 :          IF (use_rfo) THEN
     201              :             WRITE (UNIT=output_unit, FMT="(/,T2,A,T78,A3)") &
     202            6 :                "BFGS| Use rational function optimization for step estimation: ", "YES"
     203              :          ELSE
     204              :             WRITE (UNIT=output_unit, FMT="(/,T2,A,T78,A3)") &
     205          470 :                "BFGS| Use rational function optimization for step estimation: ", " NO"
     206              :          END IF
     207          476 :          IF (use_mod_hes) THEN
     208              :             WRITE (UNIT=output_unit, FMT="(T2,A,T78,A3)") &
     209          410 :                "BFGS| Use model Hessian for initial guess: ", "YES"
     210              :          ELSE
     211              :             WRITE (UNIT=output_unit, FMT="(T2,A,T78,A3)") &
     212           66 :                "BFGS| Use model Hessian for initial guess: ", " NO"
     213              :          END IF
     214          476 :          IF (hesrest) THEN
     215              :             WRITE (UNIT=output_unit, FMT="(T2,A,T78,A3)") &
     216            4 :                "BFGS| Restart Hessian: ", "YES"
     217              :          ELSE
     218              :             WRITE (UNIT=output_unit, FMT="(T2,A,T78,A3)") &
     219          472 :                "BFGS| Restart Hessian: ", " NO"
     220              :          END IF
     221              :          WRITE (UNIT=output_unit, FMT="(T2,A,T61,F20.3)") &
     222          476 :             "BFGS| Trust radius: ", rad
     223              :       END IF
     224              : 
     225          905 :       ndf = SIZE(x0)
     226          905 :       IF (ndf > 3000 .AND. .NOT. inverse) THEN
     227              :          CALL cp_warn(__LOCATION__, &
     228              :                       "The dimension of the Hessian matrix ("// &
     229              :                       TRIM(ADJUSTL(cp_to_string(ndf)))//") is greater than 3000. "// &
     230              :                       "The diagonalisation of the full Hessian  matrix needed for BFGS "// &
     231              :                       "is computationally expensive. You should consider to use the linear "// &
     232            0 :                       "scaling variant L-BFGS instead.")
     233              :       END IF
     234              : 
     235              :       ! Initialize hessian (hes = unitary matrix or model hessian )
     236              :       CALL cp_blacs_env_create(blacs_env, para_env, globenv%blacs_grid_layout, &
     237          905 :                                globenv%blacs_repeatable)
     238              :       CALL cp_fm_struct_create(fm_struct_hes, para_env=para_env, context=blacs_env, &
     239          905 :                                nrow_global=ndf, ncol_global=ndf)
     240          905 :       CALL cp_fm_create(hess_mat, fm_struct_hes, name="hess_mat")
     241              : 
     242          905 :       CALL force_env_get(force_env=force_env, subsys=subsys)
     243          905 :       CALL cp_subsys_get(subsys, atomic_kinds=atomic_kinds)
     244          905 :       CALL get_atomic_kind_set(atomic_kind_set=atomic_kinds%els, shell_present=shell_present)
     245          905 :       IF (use_mod_hes) THEN
     246          773 :          IF (shell_present) THEN
     247              :             CALL cp_warn(__LOCATION__, &
     248              :                          "No model Hessian is available for core-shell models. "// &
     249            4 :                          "A unit matrix is used as the initial Hessian.")
     250            4 :             use_mod_hes = .FALSE.
     251              :          END IF
     252          773 :          IF (gopt_env%type_id == default_cell_method_id) THEN
     253              :             CALL cp_warn(__LOCATION__, &
     254              :                          "No model Hessian is available for cell optimizations. "// &
     255            0 :                          "A unit matrix is used as the initial Hessian.")
     256            0 :             use_mod_hes = .FALSE.
     257              :          END IF
     258              :       END IF
     259              : 
     260              :       ! hess_mat stores B for DIRECT and H = B^{-1} for INVERSE.
     261              :       ! DIRECT keeps the spectral work arrays for step construction; INVERSE
     262              :       ! only needs them while building a model-Hessian initial guess.
     263          905 :       IF (.NOT. inverse .OR. (use_mod_hes .AND. .NOT. hesrest)) THEN
     264          901 :          CALL cp_fm_create(hess_tmp, fm_struct_hes, name="hess_tmp")
     265          901 :          CALL cp_fm_create(eigvec_mat, fm_struct_hes, name="eigvec_mat")
     266         2703 :          ALLOCATE (eigval(ndf))
     267         1802 :          eigval(:) = zero
     268              :       END IF
     269              : 
     270          905 :       IF (inverse) THEN
     271           10 :          IF (use_mod_hes .AND. .NOT. hesrest) THEN
     272              :             CALL build_initial_hess(hess_mat, hess_tmp, eigvec_mat, eigval, force_env, &
     273            6 :                                     use_mod_hes, .TRUE.)
     274              :          ELSE
     275            4 :             CALL cp_fm_set_all(hess_mat, alpha=zero, beta=one)
     276              :          END IF
     277              :       ELSE
     278              :          CALL build_initial_hess(hess_mat, hess_tmp, eigvec_mat, eigval, force_env, &
     279          895 :                                  use_mod_hes, .FALSE.)
     280              :       END IF
     281              : 
     282          905 :       IF (inverse .AND. ALLOCATED(eigval)) THEN
     283            6 :          CALL cp_fm_release(eigvec_mat)
     284            6 :          CALL cp_fm_release(hess_tmp)
     285            6 :          DEALLOCATE (eigval)
     286              :       END IF
     287              : 
     288              :       ! Restore the reference coordinates before symmetry setup and the first evaluation.
     289          905 :       IF (hesrest) CALL read_bfgs_hessian(geo_section, hess_mat, logger, gopt_env, x0, matrix_method)
     290              : 
     291         2715 :       ALLOCATE (xold(ndf))
     292        25493 :       xold(:) = x0(:)
     293              : 
     294         1810 :       ALLOCATE (g(ndf))
     295        25493 :       g(:) = 0.0_dp
     296              : 
     297         1810 :       ALLOCATE (gold(ndf))
     298          905 :       gold(:) = 0.0_dp
     299              : 
     300         1810 :       ALLOCATE (dx(ndf))
     301          905 :       dx(:) = 0.0_dp
     302              : 
     303         1810 :       ALLOCATE (dg(ndf))
     304          905 :       dg(:) = 0.0_dp
     305              : 
     306         1810 :       ALLOCATE (work(ndf))
     307          905 :       work(:) = 0.0_dp
     308              : 
     309         1810 :       ALLOCATE (dr(ndf))
     310          905 :       dr(:) = 0.0_dp
     311              : 
     312              :       ! find space_group
     313          905 :       CALL gopt_f_space_group_init(gopt_env, x0, geo_section, output_unit)
     314              : 
     315              :       ! Geometry optimization starts now
     316          905 :       CALL cp_iterate(logger%iter_info, increment=0, iter_nr_out=iter_nr)
     317          905 :       CALL print_geo_opt_header(gopt_env, output_unit, wildcard)
     318              : 
     319              :       ! Calculate Energy & Gradients
     320              :       CALL cp_eval_at(gopt_env, x0, etot, g, master=gopt_env%force_env%para_env%mepos, &
     321          905 :                       para_env=gopt_env%force_env%para_env)
     322              : 
     323              :       ! Symmetrize coordinates and forces
     324          905 :       CALL gopt_f_project_coord(gopt_env, x0)
     325          905 :       CALL gopt_f_project_vector(gopt_env, g)
     326              : 
     327              :       ! Print info at time 0
     328          905 :       emin = etot
     329          905 :       t_now = m_walltime()
     330          905 :       t_diff = t_now - t_old
     331          905 :       t_old = t_now
     332          905 :       CALL gopt_f_io_init(gopt_env, output_unit, etot, wildcard=wildcard, its=iter_nr, used_time=t_diff)
     333         4392 :       DO its = iter_nr + 1, maxiter
     334         4382 :          CALL cp_iterate(logger%iter_info, last=(its == maxiter))
     335         4382 :          CALL section_vals_val_set(geo_section, "STEP_START_VAL", i_val=its)
     336         4382 :          CALL gopt_f_ii(its, output_unit)
     337              : 
     338         4382 :          IF ((its - iter_nr) > 1) THEN
     339              :             ! Symmetrize old coordinates and old forces.
     340         3487 :             CALL gopt_f_project_coord(gopt_env, xold)
     341         3487 :             CALL gopt_f_project_vector(gopt_env, gold)
     342              : 
     343              :             ! cp_eval_at may project the proposed geometry: use the actual displacement.
     344       326215 :             dx(:) = x0(:) - xold(:)
     345       326215 :             dg(:) = g(:) - gold(:)
     346         3487 :             IF (inverse) THEN
     347          502 :                CALL bfgs_inverse_update(ndf, dx, dg, hess_mat, work)
     348              :             ELSE
     349         2985 :                CALL bfgs(ndf, dx, dg, hess_mat, work, para_env, output_unit, hess_reset)
     350         2985 :                IF (hess_reset) THEN
     351              :                   CALL build_initial_hess(hess_mat, hess_tmp, eigvec_mat, eigval, force_env, &
     352            0 :                                           use_mod_hes, .FALSE.)
     353              :                END IF
     354              :             END IF
     355              : 
     356         3487 :             CALL gopt_f_project_vector(gopt_env, dx)
     357         3487 :             CALL gopt_f_project_vector(gopt_env, dg)
     358              : 
     359         3487 :             IF (BTEST(cp_print_key_should_output(logger%iter_info, print_key), cp_p_file)) THEN
     360         3162 :                CALL write_bfgs_hessian(geo_section, hess_mat, logger, gopt_env, matrix_method)
     361              :             END IF
     362              :          END IF
     363              : 
     364              :          ! Symmetrize coordinates and forces
     365         4382 :          CALL gopt_f_project_coord(gopt_env, x0)
     366         4382 :          CALL gopt_f_project_vector(gopt_env, g)
     367              : 
     368              :          ! Setting the present positions & gradients as old
     369       351554 :          xold(:) = x0
     370       351554 :          gold(:) = g
     371              : 
     372         4382 :          IF (inverse) THEN
     373          512 :             CALL bfgs_inverse_step(hess_mat, g, dr)
     374              :          ELSE
     375              :             ! Copying hessian hes to (ndf x ndf) matrix hes_mat for diagonalization
     376         3870 :             CALL cp_fm_to_fm(hess_mat, hess_tmp)
     377              : 
     378         3870 :             CALL choose_eigv_solver(hess_tmp, eigvec_mat, eigval, info=info)
     379              : 
     380              :             ! In rare cases the diagonalization of hess_mat fails (bug in scalapack?)
     381         3870 :             IF (info /= 0) THEN
     382            0 :                IF (output_unit > 0) THEN
     383              :                   WRITE (output_unit, *) &
     384            0 :                      "BFGS: Matrix diagonalization failed, resetting Hessian to unity."
     385              :                END IF
     386            0 :                CALL cp_fm_set_all(hess_mat, alpha=zero, beta=one)
     387            0 :                CALL cp_fm_to_fm(hess_mat, hess_tmp)
     388            0 :                CALL choose_eigv_solver(hess_tmp, eigvec_mat, eigval)
     389              :             END IF
     390              : 
     391         3870 :             IF (use_rfo) THEN
     392          530 :                CALL set_hes_eig(ndf, eigval, work)
     393        70634 :                dx(:) = eigval
     394          530 :                CALL rat_fun_opt(ndf, dg, eigval, work, eigvec_mat, g, para_env)
     395              :             END IF
     396         3870 :             CALL geoopt_get_step(ndf, eigval, eigvec_mat, hess_tmp, dr, g, para_env, use_rfo)
     397              : 
     398              :          END IF
     399         4382 :          CALL gopt_f_project_step(gopt_env, dr)
     400              : 
     401         4382 :          IF (inverse) THEN
     402              :             ! Avoid a zero-step division and initialize the reported scale on every step.
     403          512 :             rat = 1.0_dp
     404        79712 :             step = MAXVAL(ABS(dr))
     405          512 :             IF (step > rad) THEN
     406           16 :                rat = rad/step
     407         1864 :                dr(:) = rat*dr(:)
     408              :                step = rad
     409              :             END IF
     410              :          ELSE
     411         3870 :             CALL trust_radius(ndf, step, rad, rat, dr, output_unit)
     412              :          END IF
     413              : 
     414              :          ! Update the atomic positions
     415       351554 :          x0 = x0 + dr
     416              : 
     417              :          ! Symmetrize coordinates
     418         4382 :          CALL gopt_f_project_coord(gopt_env, x0)
     419              : 
     420         4382 :          eold = etot
     421              : 
     422              :          ! Energy & Gradients at new step
     423              :          CALL cp_eval_at(gopt_env, x0, etot, g, master=gopt_env%force_env%para_env%mepos, &
     424         4382 :                          para_env=gopt_env%force_env%para_env)
     425              : 
     426              :          ! Use the displacement actually accepted by constraints and cell projection.
     427       351554 :          dr(:) = x0(:) - xold(:)
     428       351554 :          step = MAXVAL(ABS(dr))
     429              : 
     430              :          ! This diagnostic requires B, not H. It is optional in gopt_f_io.
     431         4382 :          IF (.NOT. inverse) CALL energy_predict(ndf, work, hess_mat, dr, gold, pred, para_env)
     432              : 
     433         4382 :          ediff = etot - eold
     434              : 
     435              :          ! Symmetrize forces
     436         4382 :          CALL gopt_f_project_vector(gopt_env, g)
     437              : 
     438              :          ! check for an external exit command
     439         4382 :          CALL external_control(should_stop, "GEO", globenv=globenv)
     440         4382 :          IF (should_stop) EXIT
     441              : 
     442              :          ! Some IO and Convergence check
     443         4382 :          t_now = m_walltime()
     444         4382 :          t_diff = t_now - t_old
     445         4382 :          t_old = t_now
     446         4382 :          IF (inverse) THEN
     447              :             CALL gopt_f_io(gopt_env, force_env, root_section, its, etot, output_unit, &
     448              :                            eold, emin, wildcard, gopt_param, ndf, dr, g, conv, &
     449          512 :                            rat=rat, step=step, rad=rad, used_time=t_diff)
     450              :          ELSE
     451              :             CALL gopt_f_io(gopt_env, force_env, root_section, its, etot, output_unit, &
     452              :                            eold, emin, wildcard, gopt_param, ndf, dr, g, conv, pred, rat, &
     453         3870 :                            step, rad, used_time=t_diff)
     454              :          END IF
     455              : 
     456         4382 :          IF (conv .OR. (its == maxiter)) EXIT
     457         3487 :          IF (etot < emin) emin = etot
     458        13156 :          IF (use_rfo) CALL update_trust_rad(rat, rad, step, ediff)
     459              :       END DO
     460              : 
     461          905 :       IF (its == maxiter .AND. (.NOT. conv)) THEN
     462          627 :          CALL print_geo_opt_nc(gopt_env, output_unit)
     463              :       END IF
     464              : 
     465              :       ! show space_group
     466          905 :       CALL gopt_f_space_group_show(gopt_env, geo_section, output_unit)
     467              : 
     468              :       ! Write final  information, if converged
     469          905 :       CALL cp_iterate(logger%iter_info, last=.TRUE., increment=0)
     470          905 :       CALL write_bfgs_hessian(geo_section, hess_mat, logger, gopt_env, matrix_method)
     471              :       CALL gopt_f_io_finalize(gopt_env, force_env, x0, conv, its, root_section, &
     472          905 :                               gopt_env%force_env%para_env, gopt_env%force_env%para_env%mepos, output_unit)
     473              : 
     474          905 :       CALL cp_fm_struct_release(fm_struct_hes)
     475          905 :       CALL cp_fm_release(hess_mat)
     476          905 :       IF (.NOT. inverse) THEN
     477          895 :          CALL cp_fm_release(eigvec_mat)
     478          895 :          CALL cp_fm_release(hess_tmp)
     479              :       END IF
     480              : 
     481          905 :       CALL cp_blacs_env_release(blacs_env)
     482          905 :       DEALLOCATE (xold)
     483          905 :       DEALLOCATE (g)
     484          905 :       DEALLOCATE (gold)
     485          905 :       DEALLOCATE (dx)
     486          905 :       DEALLOCATE (dg)
     487          905 :       IF (ALLOCATED(eigval)) DEALLOCATE (eigval)
     488          905 :       DEALLOCATE (work)
     489          905 :       DEALLOCATE (dr)
     490              : 
     491              :       CALL cp_print_key_finished_output(output_unit, logger, geo_section, &
     492          905 :                                         "PRINT%PROGRAM_RUN_INFO")
     493          905 :       CALL timestop(handle)
     494              : 
     495         7240 :    END SUBROUTINE geoopt_bfgs
     496              : 
     497              : ! **************************************************************************************************
     498              : !> \brief Damped inverse-BFGS update, using only a matvec and local rank-two updates.
     499              : !> \param ndf Number of optimization variables
     500              : !> \param dx Actual change of optimization variables (not modified by damping)
     501              : !> \param dg Change of gradients in the same coordinate system
     502              : !> \param hess_mat Inverse Hessian, updated in place
     503              : !> \param work Replicated workspace for H*dg
     504              : ! **************************************************************************************************
     505          502 :    SUBROUTINE bfgs_inverse_update(ndf, dx, dg, hess_mat, work)
     506              :       INTEGER, INTENT(IN)                                :: ndf
     507              :       REAL(KIND=dp), INTENT(IN)                          :: dx(ndf), dg(ndf)
     508              :       TYPE(cp_fm_type), INTENT(IN)                       :: hess_mat
     509              :       REAL(KIND=dp), INTENT(OUT)                         :: work(ndf)
     510              : 
     511              :       REAL(KIND=dp), PARAMETER                           :: min_curvature = 0.2_dp
     512              : 
     513              :       INTEGER                                            :: handle, i, ig, invalid, j, jg, nc, nr
     514          502 :       INTEGER, DIMENSION(:), POINTER                     :: cols, rows
     515              :       REAL(KIND=dp)                                      :: coeff, rho, sy, theta, yhy
     516              :       REAL(KIND=dp), CONTIGUOUS, DIMENSION(:, :), &
     517          502 :          POINTER                                         :: data
     518          502 :       REAL(KIND=dp), DIMENSION(ndf)                      :: secant
     519              : 
     520          502 :       CALL timeset("bfgs_inverse_update", handle)
     521       157856 :       IF (.NOT. ALL(ieee_is_finite(dx)) .OR. .NOT. ALL(ieee_is_finite(dg))) THEN
     522            0 :          CPABORT("Non-finite displacement or gradient difference in inverse BFGS")
     523              :       END IF
     524        78928 :       work = 0.0_dp
     525       157354 :       IF (NORM2(dx) == 0.0_dp .OR. NORM2(dg) == 0.0_dp) THEN
     526            0 :          CALL timestop(handle)
     527            0 :          RETURN
     528              :       END IF
     529              : 
     530          502 :       CALL cp_fm_matvec(hess_mat, dg, work)
     531        78928 :       sy = DOT_PRODUCT(dx, dg)
     532        78928 :       yhy = DOT_PRODUCT(dg, work)
     533          502 :       IF (.NOT. ieee_is_finite(sy) .OR. .NOT. ieee_is_finite(yhy)) THEN
     534            0 :          CPABORT("Non-finite curvature in inverse BFGS")
     535              :       END IF
     536          502 :       IF (yhy <= 0.0_dp) THEN
     537              :          CALL cp_warn(__LOCATION__, &
     538            0 :                       "BFGS: non-positive inverse curvature; resetting to unity.")
     539            0 :          CALL cp_fm_set_all(hess_mat, alpha=0.0_dp, beta=1.0_dp)
     540            0 :          CALL timestop(handle)
     541            0 :          RETURN
     542              :       END IF
     543              : 
     544        78928 :       secant = dx
     545          502 :       IF (sy < min_curvature*yhy) THEN
     546              :          ! Dual-space damping: y^T*s_tilde >= min_curvature*y^T*H*y.
     547              :          ! Unlike damping y with B*s, this does not need the direct Hessian.
     548            4 :          theta = ((1.0_dp - min_curvature)*yhy)/(yhy - sy)
     549          712 :          secant = theta*dx + (1.0_dp - theta)*work
     550          712 :          sy = DOT_PRODUCT(secant, dg)
     551              :       END IF
     552          502 :       IF (sy <= TINY(1.0_dp)/EPSILON(1.0_dp)) THEN
     553            0 :          CALL timestop(handle)
     554            0 :          RETURN
     555              :       END IF
     556          502 :       rho = 1.0_dp/sy
     557          502 :       coeff = (1.0_dp + yhy*rho)*rho
     558          502 :       IF (.NOT. ieee_is_finite(coeff)) THEN
     559              :          CALL cp_warn(__LOCATION__, &
     560            0 :                       "BFGS: unrepresentable inverse update; retaining the previous matrix.")
     561            0 :          CALL timestop(handle)
     562            0 :          RETURN
     563              :       END IF
     564              : 
     565              :       CALL cp_fm_get_info(hess_mat, row_indices=rows, col_indices=cols, &
     566          502 :                           local_data=DATA, nrow_local=nr, ncol_local=nc)
     567          502 :       !$OMP PARALLEL DO DEFAULT(NONE) SHARED(nc,nr,rows,cols,data,coeff,rho,secant,work) PRIVATE(i,j,ig,jg)
     568              :       DO j = 1, nc
     569              :          jg = cols(j)
     570              :          DO i = 1, nr
     571              :             ig = rows(i)
     572              :             DATA(i, j) = DATA(i, j) + coeff*(secant(ig)*secant(jg)) - &
     573              :                          rho*(secant(ig)*work(jg) + work(ig)*secant(jg))
     574              :          END DO
     575              :       END DO
     576              :       !$OMP END PARALLEL DO
     577          502 :       invalid = 0
     578      6569539 :       IF (.NOT. ALL(ieee_is_finite(DATA(1:nr, 1:nc)))) invalid = 1
     579          502 :       CALL hess_mat%matrix_struct%para_env%max(invalid)
     580          502 :       IF (invalid /= 0) THEN
     581              :          CALL cp_warn(__LOCATION__, &
     582            0 :                       "BFGS: non-finite inverse matrix; resetting to unity.")
     583            0 :          CALL cp_fm_set_all(hess_mat, alpha=0.0_dp, beta=1.0_dp)
     584              :       END IF
     585          502 :       CALL timestop(handle)
     586          502 :    END SUBROUTINE bfgs_inverse_update
     587              : 
     588              : ! **************************************************************************************************
     589              : !> \brief Form -H*g and recover a descent direction if roundoff has corrupted H.
     590              : !> \param hess_mat Inverse Hessian
     591              : !> \param g Gradient
     592              : !> \param dr Search direction
     593              : ! **************************************************************************************************
     594          512 :    SUBROUTINE bfgs_inverse_step(hess_mat, g, dr)
     595              :       TYPE(cp_fm_type), INTENT(IN)                       :: hess_mat
     596              :       REAL(KIND=dp), INTENT(IN)                          :: g(:)
     597              :       REAL(KIND=dp), INTENT(OUT)                         :: dr(:)
     598              : 
     599              :       REAL(KIND=dp)                                      :: slope
     600              : 
     601        79712 :       IF (.NOT. ALL(ieee_is_finite(g))) THEN
     602            0 :          CALL cp_abort(__LOCATION__, "Non-finite gradient in inverse BFGS")
     603              :       END IF
     604        79712 :       dr = 0.0_dp
     605        79712 :       IF (MAXVAL(ABS(g)) == 0.0_dp) RETURN
     606          512 :       CALL cp_fm_matvec(hess_mat, g, dr, alpha=-1.0_dp)
     607        79712 :       slope = DOT_PRODUCT(g, dr)
     608          512 :       IF (.NOT. ieee_is_finite(slope) .OR. slope >= 0.0_dp) THEN
     609              :          CALL cp_warn(__LOCATION__, &
     610            0 :                       "BFGS: inverse matrix is not a descent model; resetting to unity.")
     611            0 :          CALL cp_fm_set_all(hess_mat, alpha=0.0_dp, beta=1.0_dp)
     612          512 :          dr = -g
     613              :       END IF
     614              :    END SUBROUTINE bfgs_inverse_step
     615              : 
     616              : ! **************************************************************************************************
     617              : !> \brief Convert a restart matrix once, not during normal inverse-BFGS iterations.
     618              : !> \param matrix Input matrix, replaced by its (regularized) inverse
     619              : !> \param from_inverse Whether the input already represents the inverse Hessian
     620              : ! **************************************************************************************************
     621            6 :    SUBROUTINE bfgs_invert_matrix(matrix, from_inverse)
     622              :       TYPE(cp_fm_type), INTENT(IN)                       :: matrix
     623              :       LOGICAL, INTENT(IN)                                :: from_inverse
     624              : 
     625              :       INTEGER                                            :: handle, info, ndf
     626              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:)           :: eigenvalues
     627              :       TYPE(cp_fm_struct_type), POINTER                   :: matrix_struct
     628              :       TYPE(cp_fm_type)                                   :: eigenvectors, scratch
     629              : 
     630            6 :       CALL timeset("bfgs_invert_matrix", handle)
     631            6 :       CALL cp_fm_get_info(matrix, matrix_struct=matrix_struct, nrow_global=ndf)
     632            6 :       CALL cp_fm_create(scratch, matrix_struct, name="bfgs_restart_scratch")
     633            6 :       CALL cp_fm_create(eigenvectors, matrix_struct, name="bfgs_restart_eigenvectors")
     634           18 :       ALLOCATE (eigenvalues(ndf))
     635            6 :       CALL cp_fm_to_fm(matrix, scratch)
     636            6 :       CALL choose_eigv_solver(scratch, eigenvectors, eigenvalues, info=info)
     637            6 :       IF (info /= 0) THEN
     638            0 :          CALL cp_abort(__LOCATION__, "BFGS restart matrix diagonalization failed")
     639              :       END IF
     640          246 :       IF (.NOT. ALL(ieee_is_finite(eigenvalues))) THEN
     641            0 :          CALL cp_abort(__LOCATION__, "Non-finite BFGS restart spectrum")
     642              :       END IF
     643            6 :       IF (from_inverse) THEN
     644              :          ! Do not apply the direct-Hessian cutoff to inverse-Hessian eigenvalues.
     645          220 :          IF (MINVAL(eigenvalues) <= 0.0_dp) THEN
     646              :             CALL cp_abort(__LOCATION__, &
     647            0 :                           "BFGS inverse restart matrix is not positive definite")
     648              :          END IF
     649              :       ELSE
     650           26 :          IF (MINVAL(eigenvalues) < min_hessian_eigenvalue) THEN
     651              :             CALL cp_warn(__LOCATION__, &
     652            0 :                          "BFGS: regularizing the direct restart before conversion to INVERSE.")
     653              :          END IF
     654           26 :          eigenvalues(:) = MAX(min_hessian_eigenvalue, eigenvalues(:))
     655              :       END IF
     656          246 :       eigenvalues(:) = 1.0_dp/eigenvalues(:)
     657          246 :       IF (.NOT. ALL(ieee_is_finite(eigenvalues))) THEN
     658              :          CALL cp_abort(__LOCATION__, &
     659            0 :                        "Unrepresentable inverse of BFGS restart matrix")
     660              :       END IF
     661            6 :       CALL cp_fm_to_fm(eigenvectors, scratch)
     662            6 :       CALL cp_fm_column_scale(scratch, eigenvalues)
     663            6 :       CALL parallel_gemm("N", "T", ndf, ndf, ndf, 1.0_dp, scratch, eigenvectors, 0.0_dp, matrix)
     664            6 :       CALL cp_fm_release(scratch)
     665            6 :       CALL cp_fm_release(eigenvectors)
     666            6 :       DEALLOCATE (eigenvalues)
     667            6 :       CALL timestop(handle)
     668           12 :    END SUBROUTINE bfgs_invert_matrix
     669              : 
     670              : ! **************************************************************************************************
     671              : !> \brief Read the metadata of a tagged BFGS restart, or identify a legacy raw Hessian.
     672              : !> \param unit File unit, returned positioned at the first matrix column
     673              : !> \param stored_method Matrix representation in the file
     674              : !> \param stored_ndf Matrix dimension stored in a tagged file; zero for legacy files
     675              : !> \param stored_type Optimization type stored in a tagged file; zero for legacy files
     676              : !> \param tagged Whether the file contains coordinate and representation metadata
     677              : !> \param reference_cell Stored CELL_OPT reference cell
     678              : !> \param cell_frame Stored canonical-to-input cell frame
     679              : ! **************************************************************************************************
     680            8 :    SUBROUTINE bfgs_read_restart_header(unit, stored_method, stored_ndf, stored_type, tagged, &
     681              :                                        reference_cell, cell_frame)
     682              :       INTEGER, INTENT(IN)                                :: unit
     683              :       INTEGER, INTENT(OUT)                               :: stored_method, stored_ndf, stored_type
     684              :       LOGICAL, INTENT(OUT)                               :: tagged
     685              :       REAL(KIND=dp), DIMENSION(3, 3), INTENT(OUT)        :: reference_cell, cell_frame
     686              : 
     687              :       CHARACTER(LEN=16)                                  :: magic
     688              :       INTEGER                                            :: ios, version
     689              : 
     690            8 :       stored_method = bfgs_direct
     691            8 :       stored_ndf = 0
     692            8 :       stored_type = 0
     693            8 :       reference_cell = 0.0_dp
     694            8 :       cell_frame = 0.0_dp
     695            8 :       magic = ""
     696            8 :       READ (unit, IOSTAT=ios) magic
     697            8 :       tagged = ios == 0 .AND. magic == bfgs_restart_magic
     698            8 :       REWIND (unit)
     699            8 :       IF (tagged) THEN
     700            8 :          READ (unit, IOSTAT=ios) magic, version, stored_method, stored_ndf, stored_type, &
     701           16 :             reference_cell, cell_frame
     702            8 :          IF (ios /= 0) CPABORT("Invalid BFGS restart header")
     703            8 :          IF (version /= bfgs_restart_version) THEN
     704            0 :             CALL cp_abort(__LOCATION__, "Unsupported BFGS restart version")
     705              :          END IF
     706            8 :          IF (stored_method /= bfgs_direct .AND. stored_method /= bfgs_inverse) THEN
     707            0 :             CPABORT("Unknown matrix representation in BFGS restart")
     708              :          END IF
     709            8 :          IF (stored_ndf <= 0) CPABORT("Invalid matrix dimension in BFGS restart")
     710          208 :          IF (.NOT. ALL(ieee_is_finite(reference_cell)) .OR. .NOT. ALL(ieee_is_finite(cell_frame))) THEN
     711            0 :             CPABORT("Non-finite coordinate frame in BFGS restart")
     712              :          END IF
     713              :       END IF
     714            8 :    END SUBROUTINE bfgs_read_restart_header
     715              : 
     716              : ! **************************************************************************************************
     717              : !> \brief Read and validate a tagged or legacy BFGS restart on the I/O rank.
     718              : !> \param unit File unit, returned positioned at the first matrix column
     719              : !> \param ndf Expected dimension
     720              : !> \param opt_type Expected optimization type
     721              : !> \param stored_method Matrix representation in the file
     722              : !> \param tagged Whether the file contains coordinate and representation metadata
     723              : !> \param reference_cell Stored CELL_OPT reference cell
     724              : !> \param cell_frame Stored canonical-to-input cell frame
     725              : ! **************************************************************************************************
     726            4 :    SUBROUTINE bfgs_read_header(unit, ndf, opt_type, stored_method, tagged, reference_cell, cell_frame)
     727              :       INTEGER, INTENT(IN)                                :: unit, ndf, opt_type
     728              :       INTEGER, INTENT(OUT)                               :: stored_method
     729              :       LOGICAL, INTENT(OUT)                               :: tagged
     730              :       REAL(KIND=dp), DIMENSION(3, 3), INTENT(OUT)        :: reference_cell, cell_frame
     731              : 
     732              :       INTEGER                                            :: ios, j, stored_ndf, stored_type
     733              :       REAL(KIND=dp)                                      :: extra
     734            8 :       REAL(KIND=dp), DIMENSION(ndf)                      :: column
     735              : 
     736              :       CALL bfgs_read_restart_header(unit, stored_method, stored_ndf, stored_type, tagged, &
     737            4 :                                     reference_cell, cell_frame)
     738            4 :       IF (tagged) THEN
     739            4 :          IF (stored_ndf /= ndf) THEN
     740              :             CALL cp_abort(__LOCATION__, &
     741            0 :                           "BFGS restart dimension does not match the optimization variables")
     742              :          END IF
     743            4 :          IF (stored_type /= opt_type) THEN
     744            0 :             CALL cp_abort(__LOCATION__, "BFGS restart optimization type does not match")
     745              :          END IF
     746              :       END IF
     747              : 
     748              :       ! Preflight before any collective read: reject truncated/non-finite payloads and
     749              :       ! incompatible legacy dimensions with a CP2K error, not a rank-local Fortran I/O failure.
     750          136 :       DO j = 1, ndf
     751          132 :          READ (unit, IOSTAT=ios) column
     752          132 :          IF (ios /= 0) THEN
     753              :             CALL cp_abort(__LOCATION__, &
     754            0 :                           "Truncated BFGS restart or incompatible legacy matrix dimension")
     755              :          END IF
     756         9784 :          IF (.NOT. ALL(ieee_is_finite(column))) THEN
     757            0 :             CALL cp_abort(__LOCATION__, "Non-finite matrix in BFGS restart")
     758              :          END IF
     759              :       END DO
     760            4 :       READ (unit, IOSTAT=ios) extra
     761            4 :       IF (ios /= iostat_end) THEN
     762              :          CALL cp_abort(__LOCATION__, &
     763            0 :                        "Extra matrix columns or invalid trailing data in BFGS restart")
     764              :       END IF
     765            4 :       REWIND (unit)
     766            4 :       IF (tagged) READ (unit)
     767            4 :    END SUBROUTINE bfgs_read_header
     768              : 
     769              : ! **************************************************************************************************
     770              : !> \brief Read a common BFGS restart, restoring its coordinates and converting if needed.
     771              : !> \param geo_section BFGS input section
     772              : !> \param hess_mat Matrix to initialize
     773              : !> \param logger Logger
     774              : !> \param gopt_env Optimization environment
     775              : !> \param x0 Current coordinates, re-expressed in the stored reference cell for CELL_OPT
     776              : !> \param matrix_method Requested in-memory representation
     777              : ! **************************************************************************************************
     778            8 :    SUBROUTINE read_bfgs_hessian(geo_section, hess_mat, logger, gopt_env, x0, matrix_method)
     779              :       TYPE(section_vals_type), POINTER                   :: geo_section
     780              :       TYPE(cp_fm_type), INTENT(INOUT)                    :: hess_mat
     781              :       TYPE(cp_logger_type), POINTER                      :: logger
     782              :       TYPE(gopt_f_type), POINTER                         :: gopt_env
     783              :       REAL(KIND=dp), DIMENSION(:), INTENT(INOUT)         :: x0
     784              :       INTEGER, INTENT(IN)                                :: matrix_method
     785              : 
     786              :       CHARACTER(LEN=default_path_length)                 :: filename
     787              :       INTEGER                                            :: ndf, stored_method, unit
     788              :       LOGICAL                                            :: tagged
     789              :       REAL(KIND=dp), DIMENSION(3, 3)                     :: cell_frame, reference_cell
     790              :       TYPE(mp_para_env_type), POINTER                    :: para_env
     791              : 
     792            8 :       para_env => gopt_env%force_env%para_env
     793            8 :       ndf = SIZE(x0)
     794            8 :       unit = -1
     795            8 :       IF (para_env%is_source()) THEN
     796            4 :          CALL section_vals_val_get(geo_section, "BFGS%RESTART_FILE_NAME", c_val=filename)
     797            4 :          IF (LEN_TRIM(filename) == 0) filename = TRIM(logger%iter_info%project_name)//"-BFGS.Hessian"
     798              :          CALL open_file(file_name=TRIM(filename), file_status="OLD", &
     799            4 :                         file_form="UNFORMATTED", file_action="READ", unit_number=unit)
     800            4 :          CALL bfgs_read_header(unit, ndf, gopt_env%type_id, stored_method, tagged, reference_cell, cell_frame)
     801              :       END IF
     802            8 :       CALL para_env%bcast(stored_method, 0)
     803            8 :       CALL para_env%bcast(tagged, 0)
     804            8 :       CALL para_env%bcast(reference_cell, 0)
     805            8 :       CALL para_env%bcast(cell_frame, 0)
     806            8 :       CALL cp_fm_read_unformatted(hess_mat, unit)
     807            8 :       IF (para_env%is_source()) CALL close_file(unit_number=unit)
     808              : 
     809            8 :       IF (gopt_env%type_id == default_cell_method_id) THEN
     810            2 :          IF (tagged) THEN
     811            2 :             CALL bfgs_restore_cell_frame(gopt_env, x0, reference_cell, cell_frame)
     812              :          ELSE
     813              :             CALL cp_warn(__LOCATION__, "Legacy BFGS restart has no reference cell; "// &
     814            0 :                          "assuming the current CELL_OPT coordinate frame. Exact frame recovery is not possible.")
     815              :          END IF
     816              :       END IF
     817            8 :       IF (stored_method /= matrix_method) THEN
     818            6 :          CALL bfgs_invert_matrix(hess_mat, stored_method == bfgs_inverse)
     819              :       END IF
     820            8 :    END SUBROUTINE read_bfgs_hessian
     821              : 
     822              : ! **************************************************************************************************
     823              : !> \brief Re-express coordinates in the saved frame without changing physical positions.
     824              : !> \param gopt_env Optimization environment
     825              : !> \param x0 Optimization coordinates
     826              : !> \param reference_cell Reference cell that defines the stored Hessian coordinates
     827              : !> \param cell_frame Canonical-to-input cell orientation used when writing the matrix
     828              : ! **************************************************************************************************
     829            2 :    SUBROUTINE bfgs_restore_cell_frame(gopt_env, x0, reference_cell, cell_frame)
     830              :       TYPE(gopt_f_type), POINTER                         :: gopt_env
     831              :       REAL(KIND=dp), DIMENSION(:), INTENT(INOUT)         :: x0
     832              :       REAL(KIND=dp), DIMENSION(3, 3), INTENT(IN)         :: reference_cell, cell_frame
     833              : 
     834              :       INTEGER                                            :: i
     835              :       REAL(KIND=dp), DIMENSION(3, 3)                     :: transform
     836              : 
     837              :       ! A normal continuation preserves this orientation even when lengths and angles change.
     838              :       ! Do not silently attach a matrix to a separately rotated or reordered structure.
     839           26 :       IF (MAXVAL(ABS(cell_frame - gopt_env%cell_env%opt_to_input)) > 1.0E-8_dp) THEN
     840              :          CALL cp_abort(__LOCATION__, &
     841            0 :                        "BFGS restart cell orientation differs; use a matching structure or RESTART_HESSIAN F")
     842              :       END IF
     843           26 :       IF (ABS(det_3x3(reference_cell)) <= EPSILON(1.0_dp)*MAXVAL(ABS(reference_cell))**3) THEN
     844            0 :          CPABORT("Singular reference cell in BFGS restart")
     845              :       END IF
     846          134 :       transform = MATMUL(reference_cell, inv_3x3(gopt_env%h_ref))
     847           62 :       DO i = 1, SIZE(x0) - 6, 3
     848         1142 :          x0(i:i + 2) = MATMUL(transform, x0(i:i + 2))
     849              :       END DO
     850           26 :       gopt_env%h_ref = reference_cell
     851            2 :    END SUBROUTINE bfgs_restore_cell_frame
     852              : 
     853              : ! **************************************************************************************************
     854              : !> \brief ...
     855              : !> \param ndf ...
     856              : !> \param dg ...
     857              : !> \param eigval ...
     858              : !> \param work ...
     859              : !> \param eigvec_mat ...
     860              : !> \param g ...
     861              : !> \param para_env ...
     862              : ! **************************************************************************************************
     863         1060 :    SUBROUTINE rat_fun_opt(ndf, dg, eigval, work, eigvec_mat, g, para_env)
     864              : 
     865              :       INTEGER, INTENT(IN)                                :: ndf
     866              :       REAL(KIND=dp), INTENT(INOUT)                       :: dg(ndf), eigval(ndf), work(ndf)
     867              :       TYPE(cp_fm_type), INTENT(IN)                       :: eigvec_mat
     868              :       REAL(KIND=dp), INTENT(INOUT)                       :: g(ndf)
     869              :       TYPE(mp_para_env_type), OPTIONAL, POINTER          :: para_env
     870              : 
     871              :       CHARACTER(LEN=*), PARAMETER                        :: routineN = 'rat_fun_opt'
     872              :       REAL(KIND=dp), PARAMETER                           :: one = 1.0_dp
     873              : 
     874              :       INTEGER                                            :: handle, i, indf, iref, iter, j, k, l, &
     875              :                                                             maxit, ncol_local, nrow_local
     876          530 :       INTEGER, DIMENSION(:), POINTER                     :: col_indices, row_indices
     877              :       LOGICAL                                            :: bisec, conv, fail, set
     878              :       REAL(KIND=dp)                                      :: fun, fun1, fun2, fun3, fung, lam1, lam2, &
     879              :                                                             ln, lp, ssize, step, stol
     880              :       REAL(KIND=dp), CONTIGUOUS, DIMENSION(:, :), &
     881          530 :          POINTER                                         :: local_data
     882              : 
     883          530 :       CALL timeset(routineN, handle)
     884              : 
     885          530 :       stol = 1.0E-8_dp
     886          530 :       ssize = 0.2_dp
     887          530 :       maxit = 999
     888          530 :       fail = .FALSE.
     889          530 :       bisec = .FALSE.
     890              : 
     891        70634 :       dg = 0._dp
     892              : 
     893              :       CALL cp_fm_get_info(eigvec_mat, row_indices=row_indices, col_indices=col_indices, &
     894          530 :                           local_data=local_data, nrow_local=nrow_local, ncol_local=ncol_local)
     895              : 
     896        40652 :       DO i = 1, nrow_local
     897        40122 :          j = row_indices(i)
     898     10898936 :          DO k = 1, ncol_local
     899     10858284 :             l = col_indices(k)
     900     10898406 :             dg(l) = dg(l) + local_data(i, k)*g(j)
     901              :          END DO
     902              :       END DO
     903          530 :       CALL para_env%sum(dg)
     904              : 
     905          530 :       set = .FALSE.
     906              : 
     907              :       DO
     908              : 
     909              : !   calculating Lambda
     910              : 
     911          554 :          lp = 0.0_dp
     912          554 :          iref = 1
     913          554 :          ln = 0.0_dp
     914          554 :          IF (eigval(iref) < 0.0_dp) ln = eigval(iref) - 0.01_dp
     915              : 
     916          554 :          conv = .FALSE.
     917          554 :          iter = 0
     918              :          DO
     919         1260 :             iter = iter + 1
     920         1260 :             fun = 0.0_dp
     921         1260 :             fung = 0.0_dp
     922       153612 :             DO indf = 1, ndf
     923       152352 :                fun = fun + dg(indf)**2/(ln - eigval(indf))
     924       153612 :                fung = fung - dg(indf)**2/((ln - eigval(indf))**2)
     925              :             END DO
     926         1260 :             fun = fun - ln
     927         1260 :             fung = fung - one
     928         1260 :             step = fun/fung
     929         1260 :             ln = ln - step
     930         1260 :             IF (ABS(step) < stol) THEN
     931              :                conv = .TRUE.
     932              :                EXIT
     933              :             END IF
     934          706 :             IF (iter >= maxit) EXIT
     935              :          END DO
     936              :          outer: DO
     937          578 :             IF (.NOT. conv) THEN
     938          744 :                bisec = .TRUE.
     939          744 :                iter = 0
     940          744 :                maxit = 9999
     941          744 :                lam1 = 0.0_dp
     942          744 :                IF (eigval(iref) < 0.0_dp) lam1 = eigval(iref) - 0.01_dp
     943              :                fun1 = 0.0_dp
     944          744 :                DO indf = 1, ndf
     945          744 :                   fun1 = fun1 + dg(indf)**2/(lam1 - eigval(indf))
     946              :                END DO
     947           24 :                fun1 = fun1 - lam1
     948           24 :                step = ABS(lam1)/1000.0_dp
     949              :                IF (step < ssize) step = ssize
     950              :                inner: DO
     951       240000 :                   iter = iter + 1
     952       240000 :                   IF (iter > maxit) THEN
     953              :                      ln = 0.0_dp
     954          554 :                      lp = 0.0_dp
     955              :                      fail = .TRUE.
     956              :                      EXIT outer
     957              :                   END IF
     958       239976 :                   fun2 = 0.0_dp
     959       239976 :                   lam2 = lam1 - iter*step
     960      7439256 :                   DO indf = 1, ndf
     961      7439256 :                      fun2 = fun2 + dg(indf)**2/(lam2 - eigval(indf))
     962              :                   END DO
     963       239976 :                   fun2 = fun2 - lam2
     964       239976 :                   IF (fun2*fun1 < 0.0_dp) THEN
     965              :                      iter = 0
     966              :                      DO
     967            0 :                         iter = iter + 1
     968            0 :                         IF (iter > maxit) THEN
     969              :                            ln = 0.0_dp
     970              :                            lp = 0.0_dp
     971              :                            fail = .TRUE.
     972              :                            EXIT outer
     973              :                         END IF
     974            0 :                         step = (lam1 + lam2)/2
     975            0 :                         fun3 = 0.0_dp
     976            0 :                         DO indf = 1, ndf
     977            0 :                            fun3 = fun3 + dg(indf)**2/(step - eigval(indf))
     978              :                         END DO
     979            0 :                         fun3 = fun3 - step
     980              : 
     981            0 :                         IF (ABS(step - lam2) < stol) THEN
     982              :                            ln = step
     983              :                            EXIT inner
     984              :                         END IF
     985              : 
     986            0 :                         IF (fun3*fun1 < stol) THEN
     987              :                            lam2 = step
     988              :                         ELSE
     989            0 :                            lam1 = step
     990              :                         END IF
     991              :                      END DO
     992              :                   END IF
     993              :                END DO inner
     994              :             END IF
     995          554 :             IF ((ln > eigval(iref)) .OR. ((ln > 0.0_dp) .AND. &
     996              :                                           (eigval(iref) > 0.0_dp))) THEN
     997              : 
     998           24 :                IF (.NOT. bisec) THEN
     999              :                   conv = .FALSE.
    1000              :                   CYCLE outer
    1001              :                END IF
    1002              :                ln = 0.0_dp
    1003              :                lp = 0.0_dp
    1004              :                fail = .TRUE.
    1005              :             END IF
    1006              :             EXIT outer
    1007              :          END DO outer
    1008              : 
    1009          554 :          IF (fail .AND. .NOT. set) THEN
    1010          744 :             set = .TRUE.
    1011          744 :             DO indf = 1, ndf
    1012          744 :                eigval(indf) = eigval(indf)*work(indf)
    1013              :             END DO
    1014              :             CYCLE
    1015              :          END IF
    1016              : 
    1017          530 :          IF (.NOT. set) THEN
    1018        69890 :             work(1:ndf) = one
    1019              :          END IF
    1020              : 
    1021        70634 :          DO indf = 1, ndf
    1022        70634 :             eigval(indf) = eigval(indf) - ln
    1023              :          END DO
    1024              :          EXIT
    1025              :       END DO
    1026              : 
    1027          530 :       CALL timestop(handle)
    1028              : 
    1029          530 :    END SUBROUTINE rat_fun_opt
    1030              : 
    1031              : ! **************************************************************************************************
    1032              : !> \brief Update the direct Hessian with the damped BFGS formula
    1033              : !> \param ndf Number of optimization variables
    1034              : !> \param dx Change of the optimization variables
    1035              : !> \param dg Change of the gradients in the same coordinate system
    1036              : !> \param hess_mat Direct Hessian, updated in place
    1037              : !> \param work Replicated workspace, holds B*dx on exit
    1038              : !> \param para_env ...
    1039              : !> \param output_unit Geometry log unit, activates at the default MEDIUM print level
    1040              : !> \param hess_reset Set if the update had to be refused and the caller must
    1041              : !>                  collectively rebuild the initial Hessian
    1042              : ! **************************************************************************************************
    1043         5970 :    SUBROUTINE bfgs(ndf, dx, dg, hess_mat, work, para_env, output_unit, hess_reset)
    1044              :       INTEGER, INTENT(IN)                                :: ndf
    1045              :       REAL(KIND=dp), INTENT(INOUT)                       :: dx(ndf), dg(ndf)
    1046              :       TYPE(cp_fm_type), INTENT(IN)                       :: hess_mat
    1047              :       REAL(KIND=dp), INTENT(INOUT)                       :: work(ndf)
    1048              :       TYPE(mp_para_env_type), OPTIONAL, POINTER          :: para_env
    1049              :       INTEGER, INTENT(IN)                                :: output_unit
    1050              :       LOGICAL, INTENT(OUT)                               :: hess_reset
    1051              : 
    1052              :       CHARACTER(LEN=*), PARAMETER                        :: routineN = 'bfgs'
    1053              :       INTEGER, PARAMETER                                 :: exit_reset = 2, exit_skip = 1, &
    1054              :                                                             exit_update = 0
    1055              :       REAL(KIND=dp), PARAMETER                           :: min_curvature = 0.2_dp, one = 1.0_dp, &
    1056              :                                                             min_sbs = 10.0_dp*TINY(one), &
    1057              :                                                             zero = 0.0_dp
    1058              : 
    1059              :       INTEGER                                            :: exit_flag, handle, i, invalid, j, k, l, &
    1060              :                                                             ncol_local, nrow_local
    1061         2985 :       INTEGER, DIMENSION(:), POINTER                     :: col_indices, row_indices
    1062              :       REAL(KIND=dp)                                      :: dxw, eta_i, eta_j, gdx, sbs, seta, sy, &
    1063              :                                                             theta
    1064              :       REAL(KIND=dp), CONTIGUOUS, DIMENSION(:, :), &
    1065         2985 :          POINTER                                         :: local_hes
    1066              : 
    1067         2985 :       CALL timeset(routineN, handle)
    1068         2985 :       hess_reset = .FALSE.
    1069              : 
    1070              :       CALL cp_fm_get_info(hess_mat, row_indices=row_indices, col_indices=col_indices, &
    1071         2985 :                           local_data=local_hes, nrow_local=nrow_local, ncol_local=ncol_local)
    1072              : 
    1073              :       ! Refuse corrupted input instead of poisoning the Hessian with Inf/NaN.
    1074       494574 :       IF (.NOT. ALL(ieee_is_finite(dx(1:ndf))) .OR. .NOT. ALL(ieee_is_finite(dg(1:ndf)))) THEN
    1075            0 :          CPABORT("Non-finite displacement or gradient difference")
    1076              :       END IF
    1077              : 
    1078       247287 :       work = zero
    1079       145209 :       DO i = 1, nrow_local
    1080       142224 :          j = row_indices(i)
    1081     23215557 :          DO k = 1, ncol_local
    1082     23070348 :             l = col_indices(k)
    1083     23212572 :             work(j) = work(j) + local_hes(i, k)*dx(l)
    1084              :          END DO
    1085              :       END DO
    1086              : 
    1087         2985 :       IF (PRESENT(para_env)) CALL para_env%sum(work)
    1088              : 
    1089       247287 :       sy = DOT_PRODUCT(dg(1:ndf), dx(1:ndf))
    1090       247287 :       sbs = DOT_PRODUCT(dx(1:ndf), work(1:ndf))
    1091              : 
    1092              :       ! One collective decision covers every early exit, so that all ranks
    1093              :       ! take the same path. sbs and sy share the units of the energy, so the
    1094              :       ! curvature floor is relative to sy. min_sbs only fences off values for
    1095              :       ! which the divisions in the update below would overflow: with a
    1096              :       ! smaller sbs, 0.2*sbs (the least possible seta) falls below the
    1097              :       ! smallest normal number. The floor is never negative, so a non-positive
    1098              :       ! sbs (lost positive definiteness) is caught as well.
    1099         2985 :       exit_flag = exit_update
    1100       494574 :       IF (DOT_PRODUCT(dx(1:ndf), dx(1:ndf)) == zero .OR. &
    1101              :           DOT_PRODUCT(dg(1:ndf), dg(1:ndf)) == zero) THEN
    1102            0 :          exit_flag = exit_skip
    1103         2985 :       ELSE IF (.NOT. ieee_is_finite(sy) .OR. .NOT. ieee_is_finite(sbs) .OR. &
    1104              :                sbs <= MAX(EPSILON(one)*ABS(sy), min_sbs)) THEN
    1105            0 :          exit_flag = exit_reset
    1106              :       END IF
    1107              :       ! The max folds the votes into the most conservative action all ranks
    1108              :       ! can agree on. The exit codes are ordered by severity, so a skip vote
    1109              :       ! on one rank and a reset vote on another reset both. Every rank takes
    1110              :       ! the same branch, so the rebuild stays collective.
    1111         2985 :       IF (PRESENT(para_env)) CALL para_env%max(exit_flag)
    1112              : 
    1113         2985 :       IF (exit_flag == exit_skip) THEN
    1114              :          ! A zero displacement or gradient difference carries no curvature
    1115              :          ! information, so there is nothing to learn from this step.
    1116         2985 :       ELSE IF (exit_flag == exit_reset) THEN
    1117              :          ! The Hessian has lost positive definiteness along dx or the predicted
    1118              :          ! curvature is not representable, so the secant pair cannot be damped:
    1119              :          ! the caller restarts from the initial Hessian and skips this update.
    1120              :          CALL cp_warn(__LOCATION__, &
    1121            0 :                       "BFGS: vanishing or non-positive predicted curvature, resetting the Hessian")
    1122            0 :          hess_reset = .TRUE.
    1123              :       ELSE
    1124              :          ! Damped update after M.J.D. Powell, Lecture Notes in Mathematics 630 (1978),
    1125              :          ! eq. 3.7: whenever the measured curvature sy drops below 20% of the predicted
    1126              :          ! curvature s.B.s, replace y by eta = theta*y + (1-theta)*B*s. The blended
    1127              :          ! curvature satisfies eta.s = 0.2*s.B.s exactly, so the update stays positive
    1128              :          ! definite in exact arithmetic, also for secant pairs that no line search
    1129              :          ! checked. Because sbs passed the floor above, seta >= 0.2*sbs stays a
    1130              :          ! normal number, so one/seta cannot overflow and no further floor on seta
    1131              :          ! is needed.
    1132         2985 :          theta = one
    1133         2985 :          IF (sy < min_curvature*sbs) THEN
    1134           65 :             theta = ((one - min_curvature)*sbs)/(sbs - sy)
    1135           65 :             IF (output_unit > 0) THEN
    1136              :                WRITE (UNIT=output_unit, FMT="(T2,A,F10.4,A,F3.1,A)") &
    1137           26 :                   "BFGS| Damped update, curvature ratio y.s/(s.B.s): ", sy/sbs, &
    1138           52 :                   " (threshold ", min_curvature, ")"
    1139           26 :                CALL m_flush(output_unit)
    1140              :             END IF
    1141              :          END IF
    1142         2985 :          seta = theta*sy + (one - theta)*sbs
    1143         2985 :          gdx = one/seta
    1144         2985 :          dxw = one/sbs
    1145              : 
    1146       145209 :          DO i = 1, nrow_local
    1147       142224 :             j = row_indices(i)
    1148       142224 :             eta_i = theta*dg(j) + (one - theta)*work(j)
    1149     23215557 :             DO k = 1, ncol_local
    1150     23070348 :                l = col_indices(k)
    1151     23070348 :                eta_j = theta*dg(l) + (one - theta)*work(l)
    1152              :                local_hes(i, k) = local_hes(i, k) + gdx*eta_i*eta_j - &
    1153     23212572 :                                  dxw*work(j)*work(l)
    1154              :             END DO
    1155              :          END DO
    1156              : 
    1157              :          ! Collective verdict: if any local block is corrupted, every rank resets.
    1158         2985 :          invalid = 0
    1159     23317635 :          IF (.NOT. ALL(ieee_is_finite(local_hes(1:nrow_local, 1:ncol_local)))) invalid = 1
    1160         2985 :          IF (PRESENT(para_env)) CALL para_env%max(invalid)
    1161         2985 :          IF (invalid /= 0) THEN
    1162            0 :             CALL cp_warn(__LOCATION__, "BFGS: non-finite Hessian after the update, resetting")
    1163            0 :             hess_reset = .TRUE.
    1164              :          END IF
    1165              :       END IF
    1166              : 
    1167         2985 :       CALL timestop(handle)
    1168              : 
    1169         2985 :    END SUBROUTINE bfgs
    1170              : 
    1171              : ! **************************************************************************************************
    1172              : !> \brief Build the initial direct or inverse Hessian: sanitized model Hessian or unity
    1173              : !> \param hess_mat BFGS matrix (direct or inverse Hessian), replaced in place
    1174              : !> \param hess_tmp Eigensolver scratch matrix, same structure as hess_mat
    1175              : !> \param eigvec Eigensolver eigenvector matrix, same structure as hess_mat
    1176              : !> \param eigval Eigensolver workspace of length ndf
    1177              : !> \param force_env Environment providing the model Hessian at the current geometry
    1178              : !> \param use_model Build the sanitized model Hessian; otherwise fall back to unity
    1179              : !> \param inverse Store the inverse of the sanitized model Hessian
    1180              : !> \note Must be called by all ranks together: construct_initial_hess reduces internally.
    1181              : ! **************************************************************************************************
    1182          901 :    SUBROUTINE build_initial_hess(hess_mat, hess_tmp, eigvec, eigval, force_env, use_model, inverse)
    1183              :       TYPE(cp_fm_type), INTENT(IN)                       :: hess_mat, hess_tmp, eigvec
    1184              :       REAL(KIND=dp), DIMENSION(:), INTENT(OUT)           :: eigval
    1185              :       TYPE(force_env_type), POINTER                      :: force_env
    1186              :       LOGICAL, INTENT(IN)                                :: use_model, inverse
    1187              : 
    1188              :       CHARACTER(LEN=*), PARAMETER :: routineN = 'build_initial_hess'
    1189              :       REAL(KIND=dp), PARAMETER                           :: min_eig = 0.1_dp, one = 1.0_dp, &
    1190              :                                                             zero = 0.0_dp
    1191              : 
    1192              :       INTEGER                                            :: handle, indf, info, ndf
    1193              : 
    1194          901 :       CALL timeset(routineN, handle)
    1195              : 
    1196          901 :       IF (use_model) THEN
    1197          767 :          CPASSERT(ASSOCIATED(force_env))
    1198          767 :          ndf = SIZE(eigval)
    1199              :          ! The raw model Hessian is not guaranteed positive definite, so
    1200              :          ! eigenfactorize, floor the eigenvalues, and rebuild.
    1201          767 :          CALL cp_fm_set_all(hess_mat, alpha=zero)
    1202          767 :          CALL construct_initial_hess(force_env, hess_mat)
    1203          767 :          CALL cp_fm_to_fm(hess_mat, hess_tmp)
    1204          767 :          CALL choose_eigv_solver(hess_tmp, eigvec, eigval, info=info)
    1205          767 :          IF (info /= 0) THEN
    1206              :             ! In rare cases the diagonalization fails (bug in scalapack?)
    1207            0 :             CALL cp_warn(__LOCATION__, "BFGS: model Hessian diagonalization failed, using unity")
    1208            0 :             CALL cp_fm_set_all(hess_mat, alpha=zero, beta=one)
    1209            0 :             eigval = one
    1210              :          ELSE
    1211        16715 :             DO indf = 1, ndf
    1212        15948 :                IF (eigval(indf) < min_eig) eigval(indf) = min_eig
    1213        16715 :                IF (inverse) eigval(indf) = one/eigval(indf)
    1214              :             END DO
    1215          767 :             CALL cp_fm_to_fm(eigvec, hess_tmp)
    1216          767 :             CALL cp_fm_column_scale(eigvec, eigval)
    1217          767 :             CALL parallel_gemm("N", "T", ndf, ndf, ndf, one, hess_tmp, eigvec, zero, hess_mat)
    1218              :          END IF
    1219              :       ELSE
    1220              :          ! No sanitized prior exists (user opt-out, cell optimization, or
    1221              :          ! core-shell model): fall back to unity. eigval mirrors the unity
    1222              :          ! spectrum, keeping the INTENT(OUT) argument defined on every path.
    1223          134 :          CALL cp_fm_set_all(hess_mat, alpha=zero, beta=one)
    1224         8558 :          eigval = one
    1225              :       END IF
    1226              : 
    1227          901 :       CALL timestop(handle)
    1228              : 
    1229          901 :    END SUBROUTINE build_initial_hess
    1230              : 
    1231              : ! **************************************************************************************************
    1232              : !> \brief ...
    1233              : !> \param ndf ...
    1234              : !> \param eigval ...
    1235              : !> \param work ...
    1236              : ! **************************************************************************************************
    1237          530 :    SUBROUTINE set_hes_eig(ndf, eigval, work)
    1238              :       INTEGER, INTENT(IN)                                :: ndf
    1239              :       REAL(KIND=dp), INTENT(INOUT)                       :: eigval(ndf), work(ndf)
    1240              : 
    1241              :       CHARACTER(LEN=*), PARAMETER                        :: routineN = 'set_hes_eig'
    1242              :       REAL(KIND=dp), PARAMETER                           :: max_eig = 1000.0_dp, max_neg = -0.5_dp, &
    1243              :                                                             max_pos = 5.0_dp, min_eig = 0.005_dp, &
    1244              :                                                             one = 1.0_dp
    1245              : 
    1246              :       INTEGER                                            :: handle, indf
    1247              : 
    1248          530 :       CALL timeset(routineN, handle)
    1249              : 
    1250        70634 :       DO indf = 1, ndf
    1251        70634 :          IF (eigval(indf) > max_eig) eigval(indf) = max_eig
    1252              :       END DO
    1253        70634 :       DO indf = 1, ndf
    1254        70634 :          IF (eigval(indf) < 0.0_dp) THEN
    1255           24 :             IF (eigval(indf) < max_neg) THEN
    1256            0 :                eigval(indf) = max_neg
    1257           24 :             ELSE IF (eigval(indf) > -min_eig) THEN
    1258           24 :                eigval(indf) = -min_eig
    1259              :             END IF
    1260        70080 :          ELSE IF (eigval(indf) < 1000.0_dp) THEN
    1261        70056 :             IF (eigval(indf) < min_eig) THEN
    1262          168 :                eigval(indf) = min_eig
    1263        69888 :             ELSE IF (eigval(indf) > max_pos) THEN
    1264            5 :                eigval(indf) = max_pos
    1265              :             END IF
    1266              :          END IF
    1267              :       END DO
    1268              : 
    1269        70634 :       DO indf = 1, ndf
    1270        70634 :          IF (eigval(indf) < 0.0_dp) THEN
    1271           24 :             work(indf) = -one
    1272              :          ELSE
    1273        70080 :             work(indf) = one
    1274              :          END IF
    1275              :       END DO
    1276              : 
    1277          530 :       CALL timestop(handle)
    1278              : 
    1279          530 :    END SUBROUTINE set_hes_eig
    1280              : 
    1281              : ! **************************************************************************************************
    1282              : !> \brief ...
    1283              : !> \param ndf ...
    1284              : !> \param eigval ...
    1285              : !> \param eigvec_mat ...
    1286              : !> \param hess_tmp ...
    1287              : !> \param dr ...
    1288              : !> \param g ...
    1289              : !> \param para_env ...
    1290              : !> \param use_rfo ...
    1291              : ! **************************************************************************************************
    1292        11610 :    SUBROUTINE geoopt_get_step(ndf, eigval, eigvec_mat, hess_tmp, dr, g, para_env, use_rfo)
    1293              : 
    1294              :       INTEGER, INTENT(IN)                                :: ndf
    1295              :       REAL(KIND=dp), INTENT(INOUT)                       :: eigval(ndf)
    1296              :       TYPE(cp_fm_type), INTENT(IN)                       :: eigvec_mat, hess_tmp
    1297              :       REAL(KIND=dp), INTENT(INOUT)                       :: dr(ndf), g(ndf)
    1298              :       TYPE(mp_para_env_type), OPTIONAL, POINTER          :: para_env
    1299              :       LOGICAL                                            :: use_rfo
    1300              : 
    1301              :       REAL(KIND=dp), PARAMETER                           :: one = 1.0_dp, zero = 0.0_dp
    1302              : 
    1303              :       INTEGER                                            :: i, indf, j, k, l, ncol_local, nrow_local
    1304         3870 :       INTEGER, DIMENSION(:), POINTER                     :: col_indices, row_indices
    1305              :       REAL(KIND=dp), CONTIGUOUS, DIMENSION(:, :), &
    1306         3870 :          POINTER                                         :: local_data
    1307              :       TYPE(cp_fm_struct_type), POINTER                   :: matrix_struct
    1308              :       TYPE(cp_fm_type)                                   :: tmp
    1309              : 
    1310         3870 :       CALL cp_fm_to_fm(eigvec_mat, hess_tmp)
    1311         3870 :       IF (use_rfo) THEN
    1312        70634 :          DO indf = 1, ndf
    1313        70634 :             eigval(indf) = one/eigval(indf)
    1314              :          END DO
    1315              :       ELSE
    1316       201208 :          DO indf = 1, ndf
    1317       201208 :             eigval(indf) = one/MAX(min_hessian_eigenvalue, eigval(indf))
    1318              :          END DO
    1319              :       END IF
    1320              : 
    1321         3870 :       CALL cp_fm_column_scale(hess_tmp, eigval)
    1322         3870 :       CALL cp_fm_get_info(eigvec_mat, matrix_struct=matrix_struct)
    1323         3870 :       CALL cp_fm_create(tmp, matrix_struct, name="tmp")
    1324         3870 :       CALL cp_fm_set_all(tmp, alpha=zero)
    1325              : 
    1326         3870 :       CALL parallel_gemm("N", "T", ndf, ndf, ndf, one, hess_tmp, eigvec_mat, zero, tmp)
    1327              : 
    1328         3870 :       CALL cp_fm_transpose(tmp, hess_tmp)
    1329         3870 :       CALL cp_fm_release(tmp)
    1330              : 
    1331              :       ! New step
    1332              : 
    1333              :       CALL cp_fm_get_info(hess_tmp, row_indices=row_indices, col_indices=col_indices, &
    1334         3870 :                           local_data=local_data, nrow_local=nrow_local, ncol_local=ncol_local)
    1335              : 
    1336       271842 :       dr = 0.0_dp
    1337       159654 :       DO i = 1, nrow_local
    1338       155784 :          j = row_indices(i)
    1339     25019346 :          DO k = 1, ncol_local
    1340     24859692 :             l = col_indices(k)
    1341     25015476 :             dr(j) = dr(j) - local_data(i, k)*g(l)
    1342              :          END DO
    1343              :       END DO
    1344              : 
    1345         3870 :       CALL para_env%sum(dr)
    1346              : 
    1347         3870 :    END SUBROUTINE geoopt_get_step
    1348              : 
    1349              : ! **************************************************************************************************
    1350              : !> \brief ...
    1351              : !> \param ndf ...
    1352              : !> \param step ...
    1353              : !> \param rad ...
    1354              : !> \param rat ...
    1355              : !> \param dr ...
    1356              : !> \param output_unit ...
    1357              : ! **************************************************************************************************
    1358         3870 :    SUBROUTINE trust_radius(ndf, step, rad, rat, dr, output_unit)
    1359              :       INTEGER, INTENT(IN)                                :: ndf
    1360              :       REAL(KIND=dp), INTENT(INOUT)                       :: step, rad, rat, dr(ndf)
    1361              :       INTEGER, INTENT(IN)                                :: output_unit
    1362              : 
    1363              :       CHARACTER(LEN=*), PARAMETER                        :: routineN = 'trust_radius'
    1364              :       REAL(KIND=dp), PARAMETER                           :: one = 1.0_dp
    1365              : 
    1366              :       INTEGER                                            :: handle
    1367              :       REAL(KIND=dp)                                      :: scal
    1368              : 
    1369         3870 :       CALL timeset(routineN, handle)
    1370              : 
    1371       271842 :       step = MAXVAL(ABS(dr))
    1372         3870 :       scal = MAX(one, rad/step)
    1373              : 
    1374         3870 :       IF (step > rad) THEN
    1375          370 :          rat = rad/step
    1376          370 :          CALL DSCAL(ndf, rat, dr, 1)
    1377          370 :          step = rad
    1378          370 :          IF (output_unit > 0) THEN
    1379              :             WRITE (unit=output_unit, FMT="(/,T2,A,F8.5)") &
    1380          195 :                " Step is scaled; Scaling factor = ", rat
    1381          195 :             CALL m_flush(output_unit)
    1382              :          END IF
    1383              :       END IF
    1384         3870 :       CALL timestop(handle)
    1385              : 
    1386         3870 :    END SUBROUTINE trust_radius
    1387              : 
    1388              : ! **************************************************************************************************
    1389              : !> \brief ...
    1390              : !> \param ndf ...
    1391              : !> \param work ...
    1392              : !> \param hess_mat ...
    1393              : !> \param dr ...
    1394              : !> \param g ...
    1395              : !> \param pred ...
    1396              : !> \param para_env ...
    1397              : ! **************************************************************************************************
    1398         7740 :    SUBROUTINE energy_predict(ndf, work, hess_mat, dr, g, pred, para_env)
    1399              : 
    1400              :       INTEGER, INTENT(IN)                                :: ndf
    1401              :       REAL(KIND=dp), INTENT(INOUT)                       :: work(ndf)
    1402              :       TYPE(cp_fm_type), INTENT(IN)                       :: hess_mat
    1403              :       REAL(KIND=dp), INTENT(INOUT)                       :: dr(ndf), g(ndf), pred
    1404              :       TYPE(mp_para_env_type), POINTER                    :: para_env
    1405              : 
    1406              :       CHARACTER(LEN=*), PARAMETER                        :: routineN = 'energy_predict'
    1407              :       REAL(KIND=dp), PARAMETER                           :: zero = 0.0_dp
    1408              : 
    1409              :       INTEGER                                            :: handle, i, j, k, l, ncol_local, &
    1410              :                                                             nrow_local
    1411         3870 :       INTEGER, DIMENSION(:), POINTER                     :: col_indices, row_indices
    1412              :       REAL(KIND=dp)                                      :: ener1, ener2
    1413              :       REAL(KIND=dp), CONTIGUOUS, DIMENSION(:, :), &
    1414         3870 :          POINTER                                         :: local_data
    1415              : 
    1416         3870 :       CALL timeset(routineN, handle)
    1417              : 
    1418       271842 :       ener1 = DOT_PRODUCT(g(1:ndf), dr(1:ndf))
    1419              : 
    1420              :       CALL cp_fm_get_info(hess_mat, row_indices=row_indices, col_indices=col_indices, &
    1421         3870 :                           local_data=local_data, nrow_local=nrow_local, ncol_local=ncol_local)
    1422              : 
    1423       271842 :       work = zero
    1424       159654 :       DO i = 1, nrow_local
    1425       155784 :          j = row_indices(i)
    1426     25019346 :          DO k = 1, ncol_local
    1427     24859692 :             l = col_indices(k)
    1428     25015476 :             work(j) = work(j) + local_data(i, k)*dr(l)
    1429              :          END DO
    1430              :       END DO
    1431              : 
    1432         3870 :       CALL para_env%sum(work)
    1433       271842 :       ener2 = DOT_PRODUCT(dr(1:ndf), work(1:ndf))
    1434         3870 :       pred = ener1 + 0.5_dp*ener2
    1435         3870 :       CALL timestop(handle)
    1436              : 
    1437         3870 :    END SUBROUTINE energy_predict
    1438              : 
    1439              : ! **************************************************************************************************
    1440              : !> \brief ...
    1441              : !> \param rat ...
    1442              : !> \param rad ...
    1443              : !> \param step ...
    1444              : !> \param ediff ...
    1445              : ! **************************************************************************************************
    1446          505 :    SUBROUTINE update_trust_rad(rat, rad, step, ediff)
    1447              : 
    1448              :       REAL(KIND=dp), INTENT(INOUT)                       :: rat, rad, step, ediff
    1449              : 
    1450              :       CHARACTER(LEN=*), PARAMETER                        :: routineN = 'update_trust_rad'
    1451              :       REAL(KIND=dp), PARAMETER                           :: max_trust = 1.0_dp, min_trust = 0.1_dp
    1452              : 
    1453              :       INTEGER                                            :: handle
    1454              : 
    1455          505 :       CALL timeset(routineN, handle)
    1456              : 
    1457          505 :       IF (rat > 4.0_dp) THEN
    1458            0 :          IF (ediff < 0.0_dp) THEN
    1459            0 :             rad = step*0.5_dp
    1460              :          ELSE
    1461            0 :             rad = step*0.25_dp
    1462              :          END IF
    1463          505 :       ELSE IF (rat > 2.0_dp) THEN
    1464            0 :          IF (ediff < 0.0_dp) THEN
    1465            0 :             rad = step*0.75_dp
    1466              :          ELSE
    1467            0 :             rad = step*0.5_dp
    1468              :          END IF
    1469          505 :       ELSE IF (rat > 4.0_dp/3.0_dp) THEN
    1470            0 :          IF (ediff < 0.0_dp) THEN
    1471            0 :             rad = step
    1472              :          ELSE
    1473            0 :             rad = step*0.75_dp
    1474              :          END IF
    1475          505 :       ELSE IF (rat > 10.0_dp/9.0_dp) THEN
    1476            0 :          IF (ediff < 0.0_dp) THEN
    1477            0 :             rad = step*1.25_dp
    1478              :          ELSE
    1479            0 :             rad = step
    1480              :          END IF
    1481          505 :       ELSE IF (rat > 0.9_dp) THEN
    1482           41 :          IF (ediff < 0.0_dp) THEN
    1483           41 :             rad = step*1.5_dp
    1484              :          ELSE
    1485            0 :             rad = step*1.25_dp
    1486              :          END IF
    1487          464 :       ELSE IF (rat > 0.75_dp) THEN
    1488          114 :          IF (ediff < 0.0_dp) THEN
    1489          109 :             rad = step*1.25_dp
    1490              :          ELSE
    1491            5 :             rad = step
    1492              :          END IF
    1493          350 :       ELSE IF (rat > 0.5_dp) THEN
    1494           42 :          IF (ediff < 0.0_dp) THEN
    1495           42 :             rad = step
    1496              :          ELSE
    1497            0 :             rad = step*0.75_dp
    1498              :          END IF
    1499          308 :       ELSE IF (rat > 0.25_dp) THEN
    1500            4 :          IF (ediff < 0.0_dp) THEN
    1501            4 :             rad = step*0.75_dp
    1502              :          ELSE
    1503            0 :             rad = step*0.5_dp
    1504              :          END IF
    1505          304 :       ELSE IF (ediff < 0.0_dp) THEN
    1506          302 :          rad = step*0.5_dp
    1507              :       ELSE
    1508            2 :          rad = step*0.25_dp
    1509              :       END IF
    1510              : 
    1511          505 :       rad = MAX(rad, min_trust)
    1512          505 :       rad = MIN(rad, max_trust)
    1513          505 :       CALL timestop(handle)
    1514              : 
    1515          505 :    END SUBROUTINE update_trust_rad
    1516              : 
    1517              : ! **************************************************************************************************
    1518              : 
    1519              : ! **************************************************************************************************
    1520              : !> \brief ...
    1521              : !> \param geo_section ...
    1522              : !> \param hess_mat ...
    1523              : !> \param logger ...
    1524              : !> \param gopt_env Optimization coordinate system
    1525              : !> \param matrix_method Stored matrix representation
    1526              : ! **************************************************************************************************
    1527         8134 :    SUBROUTINE write_bfgs_hessian(geo_section, hess_mat, logger, gopt_env, matrix_method)
    1528              : 
    1529              :       TYPE(section_vals_type), POINTER                   :: geo_section
    1530              :       TYPE(cp_fm_type), INTENT(IN)                       :: hess_mat
    1531              :       TYPE(cp_logger_type), POINTER                      :: logger
    1532              :       TYPE(gopt_f_type), POINTER                         :: gopt_env
    1533              :       INTEGER, INTENT(IN)                                :: matrix_method
    1534              : 
    1535              :       CHARACTER(LEN=*), PARAMETER :: routineN = 'write_bfgs_hessian'
    1536              : 
    1537              :       INTEGER                                            :: handle, hesunit, ndf
    1538              :       REAL(KIND=dp), DIMENSION(3, 3)                     :: cell_frame
    1539              : 
    1540         4067 :       CALL timeset(routineN, handle)
    1541         4067 :       CALL cp_fm_get_info(hess_mat, nrow_global=ndf)
    1542         4067 :       cell_frame = 0.0_dp
    1543        11435 :       IF (gopt_env%type_id == default_cell_method_id) cell_frame = gopt_env%cell_env%opt_to_input
    1544              :       hesunit = cp_print_key_unit_nr(logger, geo_section, "BFGS%RESTART", &
    1545              :                                      extension=".Hessian", file_form="UNFORMATTED", file_action="WRITE", &
    1546         4067 :                                      file_position="REWIND")
    1547         4067 :       IF (hesunit > 0) THEN
    1548         2355 :          WRITE (hesunit) bfgs_restart_magic, bfgs_restart_version, matrix_method, ndf, &
    1549        32970 :             gopt_env%type_id, gopt_env%h_ref, cell_frame
    1550              :       END IF
    1551              :       ! Store the native representation. Conversions occur only when reading a different METHOD.
    1552         4067 :       CALL cp_fm_write_unformatted(hess_mat, hesunit)
    1553         4067 :       CALL cp_print_key_finished_output(hesunit, logger, geo_section, "BFGS%RESTART")
    1554         4067 :       CALL timestop(handle)
    1555              : 
    1556         4067 :    END SUBROUTINE write_bfgs_hessian
    1557              : 
    1558              : ! **************************************************************************************************
    1559              : !> \brief Constructs model Hessian as described in https://doi.org/10.1016/0009-2614(95)00646-L.
    1560              : !> \param force_env ...
    1561              : !> \param hess_mat ...
    1562              : !> \author Florian Schiffmann
    1563              : ! **************************************************************************************************
    1564          767 :    SUBROUTINE construct_initial_hess(force_env, hess_mat)
    1565              : 
    1566              :       TYPE(force_env_type), POINTER                      :: force_env
    1567              :       TYPE(cp_fm_type), INTENT(IN)                       :: hess_mat
    1568              : 
    1569              :       INTEGER                                            :: i, iat_col, iat_row, iglobal, iind, j, &
    1570              :                                                             jat_row, jglobal, jind, k, natom, &
    1571              :                                                             ncol_local, nrow_local, z
    1572          767 :       INTEGER, ALLOCATABLE, DIMENSION(:)                 :: at_row
    1573          767 :       INTEGER, DIMENSION(:), POINTER                     :: col_indices, row_indices
    1574              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:, :)        :: d_ij, rho_ij
    1575              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:, :, :)     :: r_ij
    1576              :       REAL(KIND=dp), CONTIGUOUS, DIMENSION(:, :), &
    1577          767 :          POINTER                                         :: fixed, local_data
    1578              :       REAL(KIND=dp), DIMENSION(3, 3)                     :: alpha, r0
    1579              :       TYPE(cell_type), POINTER                           :: cell
    1580              :       TYPE(cp_subsys_type), POINTER                      :: subsys
    1581              :       TYPE(particle_list_type), POINTER                  :: particles
    1582              : 
    1583          767 :       CALL cite_reference(Lindh1995)
    1584              : 
    1585          767 :       CALL force_env_get(force_env=force_env, subsys=subsys, cell=cell)
    1586              :       CALL cp_subsys_get(subsys, &
    1587          767 :                          particles=particles)
    1588              : 
    1589          767 :       alpha = lindh_alpha
    1590          767 :       r0 = lindh_r0
    1591              : 
    1592              :       CALL cp_fm_get_info(hess_mat, row_indices=row_indices, col_indices=col_indices, &
    1593          767 :                           local_data=local_data, nrow_local=nrow_local, ncol_local=ncol_local)
    1594          767 :       natom = particles%n_els
    1595         2301 :       ALLOCATE (at_row(natom))
    1596         3068 :       ALLOCATE (rho_ij(natom, natom))
    1597         2301 :       ALLOCATE (d_ij(natom, natom))
    1598         3835 :       ALLOCATE (r_ij(natom, natom, 3))
    1599         2301 :       ALLOCATE (fixed(3, natom))
    1600        22031 :       fixed = 1.0_dp
    1601          767 :       CALL fix_atom_control(force_env, fixed)
    1602         3068 :       DO i = 1, 3
    1603        34964 :          CALL hess_mat%matrix_struct%para_env%min(fixed(i, :))
    1604              :       END DO
    1605          767 :       rho_ij = 0
    1606         6083 :       at_row = 3
    1607         6083 :       DO i = 1, natom
    1608         5316 :          CALL get_atomic_kind(atomic_kind=particles%els(i)%atomic_kind, z=z)
    1609         5316 :          IF (z <= 10) at_row(i) = 2
    1610        11399 :          IF (z <= 2) at_row(i) = 1
    1611              :       END DO
    1612         5316 :       DO i = 2, natom
    1613         4549 :          iat_row = at_row(i)
    1614        68083 :          DO j = 1, i - 1
    1615        62767 :             jat_row = at_row(j)
    1616              :             !pbc for a distance vector
    1617       251068 :             r_ij(j, i, :) = pbc(particles%els(i)%r, particles%els(j)%r, cell)
    1618       251068 :             r_ij(i, j, :) = -r_ij(j, i, :)
    1619       251068 :             d_ij(j, i) = NORM2(r_ij(j, i, :))
    1620        62767 :             d_ij(i, j) = d_ij(j, i)
    1621        62767 :             rho_ij(j, i) = EXP(alpha(jat_row, iat_row)*(r0(jat_row, iat_row)**2 - d_ij(j, i)**2))
    1622        67316 :             rho_ij(i, j) = rho_ij(j, i)
    1623              :          END DO
    1624              :       END DO
    1625        16715 :       DO i = 1, ncol_local
    1626        15948 :          iglobal = col_indices(i)
    1627        15948 :          iind = MOD(iglobal - 1, 3) + 1
    1628        15948 :          iat_col = (iglobal + 2)/3
    1629        15948 :          IF (iat_col > natom) CYCLE
    1630       689420 :          DO j = 1, nrow_local
    1631       672705 :             jglobal = row_indices(j)
    1632       672705 :             jind = MOD(jglobal - 1, 3) + 1
    1633       672705 :             iat_row = (jglobal + 2)/3
    1634       672705 :             IF (iat_row > natom) CYCLE
    1635       672705 :             IF (iat_row /= iat_col) THEN
    1636       643608 :                IF (d_ij(iat_row, iat_col) < lindh_cutoff) THEN
    1637              :                   local_data(j, i) = local_data(j, i) + &
    1638       213120 :                                      angle_second_deriv(r_ij, d_ij, rho_ij, iind, jind, iat_col, iat_row, natom)
    1639              :                END IF
    1640              :             ELSE
    1641              :                local_data(j, i) = local_data(j, i) + &
    1642        29097 :                                   angle_second_deriv(r_ij, d_ij, rho_ij, iind, jind, iat_col, iat_row, natom)
    1643              :             END IF
    1644       672705 :             IF (iat_col /= iat_row) THEN
    1645       643608 :                IF (d_ij(iat_row, iat_col) < lindh_cutoff) THEN
    1646              :                   local_data(j, i) = local_data(j, i) - &
    1647              :                                      dist_second_deriv(r_ij(iat_col, iat_row, :), &
    1648       852480 :                                                        iind, jind, d_ij(iat_row, iat_col), rho_ij(iat_row, iat_col))
    1649              :                END IF
    1650              :             ELSE
    1651       701802 :                DO k = 1, natom
    1652       672705 :                   IF (k == iat_col) CYCLE
    1653       672705 :                   IF (d_ij(iat_row, k) < lindh_cutoff) THEN
    1654              :                      local_data(j, i) = local_data(j, i) + &
    1655              :                                         dist_second_deriv(r_ij(iat_col, k, :), &
    1656       852480 :                                                           iind, jind, d_ij(iat_row, k), rho_ij(iat_row, k))
    1657              :                   END IF
    1658              :                END DO
    1659              :             END IF
    1660       688653 :             IF (fixed(jind, iat_row) < 0.5_dp .OR. fixed(iind, iat_col) < 0.5_dp) THEN
    1661        10161 :                local_data(j, i) = 0.0_dp
    1662        10161 :                IF (jind == iind .AND. iat_row == iat_col) local_data(j, i) = 1.0_dp
    1663              :             END IF
    1664              :          END DO
    1665              :       END DO
    1666          767 :       DEALLOCATE (fixed)
    1667          767 :       DEALLOCATE (rho_ij)
    1668          767 :       DEALLOCATE (d_ij)
    1669          767 :       DEALLOCATE (r_ij)
    1670          767 :       DEALLOCATE (at_row)
    1671              : 
    1672         1534 :    END SUBROUTINE construct_initial_hess
    1673              : 
    1674              : ! **************************************************************************************************
    1675              : !> \brief ...
    1676              : !> \param r1 ...
    1677              : !> \param i ...
    1678              : !> \param j ...
    1679              : !> \param d ...
    1680              : !> \param rho ...
    1681              : !> \return ...
    1682              : ! **************************************************************************************************
    1683       426240 :    PURE FUNCTION dist_second_deriv(r1, i, j, d, rho) RESULT(deriv)
    1684              :       REAL(KIND=dp), DIMENSION(3), INTENT(IN)            :: r1
    1685              :       INTEGER, INTENT(IN)                                :: i, j
    1686              :       REAL(KIND=dp), INTENT(IN)                          :: d, rho
    1687              :       REAL(KIND=dp)                                      :: deriv
    1688              : 
    1689       426240 :       deriv = lindh_stretch_factor*rho*(r1(i)*r1(j))/d**2
    1690       426240 :    END FUNCTION dist_second_deriv
    1691              : 
    1692              : ! **************************************************************************************************
    1693              : !> \brief ...
    1694              : !> \param r_ij ...
    1695              : !> \param d_ij ...
    1696              : !> \param rho_ij ...
    1697              : !> \param idir ...
    1698              : !> \param jdir ...
    1699              : !> \param iat_der ...
    1700              : !> \param jat_der ...
    1701              : !> \param natom ...
    1702              : !> \return ...
    1703              : ! **************************************************************************************************
    1704       242217 :    FUNCTION angle_second_deriv(r_ij, d_ij, rho_ij, idir, jdir, iat_der, jat_der, natom) RESULT(deriv)
    1705              :       REAL(KIND=dp), DIMENSION(:, :, :)                  :: r_ij
    1706              :       REAL(KIND=dp), DIMENSION(:, :)                     :: d_ij, rho_ij
    1707              :       INTEGER                                            :: idir, jdir, iat_der, jat_der, natom
    1708              :       REAL(KIND=dp)                                      :: deriv
    1709              : 
    1710              :       REAL(KIND=dp), PARAMETER                           :: rho_thre = 1.0E-5_dp
    1711              : 
    1712              :       INTEGER                                            :: i, iat, idr, j, jat, jdr
    1713              :       REAL(KIND=dp)                                      :: d12, d23, d31, D_mat(3, 2), denom1, &
    1714              :                                                             denom2, denom3, ka1, ka2, ka3, rho12, &
    1715              :                                                             rho23, rho31, rsst1, rsst2, rsst3
    1716              :       REAL(KIND=dp), DIMENSION(3)                        :: r12, r23, r31
    1717              : 
    1718       242217 :       deriv = 0._dp
    1719       242217 :       IF (iat_der == jat_der) THEN
    1720       672705 :          DO i = 1, natom - 1
    1721       643608 :             IF (rho_ij(iat_der, i) < rho_thre) CYCLE
    1722      3569778 :             DO j = i + 1, natom
    1723      3344301 :                IF (rho_ij(iat_der, j) < rho_thre) CYCLE
    1724       968058 :                IF (i == iat_der .OR. j == iat_der) CYCLE
    1725       968058 :                IF (iat_der < i .OR. iat_der > j) THEN
    1726      5868270 :                   r12 = r_ij(iat_der, i, :); r23 = r_ij(i, j, :); r31 = r_ij(j, iat_der, :)
    1727       586827 :                   d12 = d_ij(iat_der, i); d23 = d_ij(i, j); d31 = d_ij(j, iat_der)
    1728       586827 :                   rho12 = rho_ij(iat_der, i); rho23 = rho_ij(i, j); rho31 = rho_ij(j, iat_der)
    1729              :                ELSE
    1730      3812310 :                   r12 = r_ij(iat_der, j, :); r23 = r_ij(j, i, :); r31 = r_ij(i, iat_der, :)
    1731       381231 :                   d12 = d_ij(iat_der, j); d23 = d_ij(j, i); d31 = d_ij(i, iat_der)
    1732       381231 :                   rho12 = rho_ij(iat_der, j); rho23 = rho_ij(j, i); rho31 = rho_ij(i, iat_der)
    1733              :                END IF
    1734       968058 :                ka1 = lindh_angle_factor*rho12*rho23; ka2 = lindh_angle_factor*rho23*rho31; ka3 = lindh_angle_factor*rho31*rho12
    1735      9680580 :                rsst1 = DOT_PRODUCT(r12, r23); rsst2 = DOT_PRODUCT(r23, r31); rsst3 = DOT_PRODUCT(r31, r12)
    1736       968058 :                denom1 = 1.0_dp - rsst1**2/(d12**2*d23**2); denom2 = 1.0_dp - rsst2**2/(d23**2*d31**2)
    1737       968058 :                denom3 = 1.0_dp - rsst3**2/(d31**2*d12**2)
    1738       968058 :                denom1 = SIGN(1.0_dp, denom1)*MAX(ABS(denom1), lindh_denom_floor)
    1739       968058 :                denom2 = SIGN(1.0_dp, denom2)*MAX(ABS(denom2), lindh_denom_floor)
    1740       968058 :                denom3 = SIGN(1.0_dp, denom3)*MAX(ABS(denom3), lindh_denom_floor)
    1741       968058 :                D_mat(1, 1) = r23(idir)/(d12*d23) - rsst1*r12(idir)/(d12**3*d23)
    1742       968058 :                D_mat(1, 2) = r23(jdir)/(d12*d23) - rsst1*r12(jdir)/(d12**3*d23)
    1743       968058 :                D_mat(2, 1) = -r23(idir)/(d23*d31) + rsst2*r31(idir)/(d23*d31**3)
    1744       968058 :                D_mat(2, 2) = -r23(jdir)/(d23*d31) + rsst2*r31(jdir)/(d23*d31**3)
    1745              :                D_mat(3, 1) = (r31(idir) - r12(idir))/(d31*d12) + rsst3*r31(idir)/(d31**3*d12) - &
    1746       968058 :                              rsst3*r12(idir)/(d31*d12**3)
    1747              :                D_mat(3, 2) = (r31(jdir) - r12(jdir))/(d31*d12) + rsst3*r31(jdir)/(d31**3*d12) - &
    1748       968058 :                              rsst3*r12(jdir)/(d31*d12**3)
    1749       968058 :                IF (ABS(denom1) <= 0.011_dp) D_mat(1, 1) = 0.0_dp
    1750       968058 :                IF (ABS(denom2) <= 0.011_dp) D_mat(2, 1) = 0.0_dp
    1751       968058 :                IF (ABS(denom3) <= 0.011_dp) D_mat(3, 1) = 0.0_dp
    1752              :                deriv = deriv + ka1*D_mat(1, 1)*D_mat(1, 2)/denom1 + &
    1753              :                        ka2*D_mat(2, 1)*D_mat(2, 2)/denom2 + &
    1754      3987909 :                        ka3*D_mat(3, 1)*D_mat(3, 2)/denom3
    1755              : 
    1756              :             END DO
    1757              :          END DO
    1758              :       ELSE
    1759      6345666 :          DO i = 1, natom
    1760      6132546 :             IF (i == iat_der .OR. i == jat_der) CYCLE
    1761      5706306 :             IF (jat_der < iat_der) THEN
    1762      2853153 :                iat = jat_der; jat = iat_der; idr = jdir; jdr = idir
    1763              :             ELSE
    1764      2853153 :                iat = iat_der; jat = jat_der; idr = idir; jdr = jdir
    1765              :             END IF
    1766      5706306 :             IF (jat < i .OR. iat > i) THEN
    1767     45387900 :                r12 = r_ij(iat, jat, :); r23 = r_ij(jat, i, :); r31 = r_ij(i, iat, :)
    1768      4538790 :                d12 = d_ij(iat, jat); d23 = d_ij(jat, i); d31 = d_ij(i, iat)
    1769      4538790 :                rho12 = rho_ij(iat, jat); rho23 = rho_ij(jat, i); rho31 = rho_ij(i, iat)
    1770              :             ELSE
    1771     11675160 :                r12 = r_ij(iat, i, :); r23 = r_ij(i, jat, :); r31 = r_ij(jat, iat, :)
    1772      1167516 :                d12 = d_ij(iat, i); d23 = d_ij(i, jat); d31 = d_ij(jat, iat)
    1773      1167516 :                rho12 = rho_ij(iat, i); rho23 = rho_ij(i, jat); rho31 = rho_ij(jat, iat)
    1774              :             END IF
    1775      5706306 :             ka1 = lindh_angle_factor*rho12*rho23; ka2 = lindh_angle_factor*rho23*rho31; ka3 = lindh_angle_factor*rho31*rho12
    1776     57063060 :             rsst1 = DOT_PRODUCT(r12, r23); rsst2 = DOT_PRODUCT(r23, r31); rsst3 = DOT_PRODUCT(r31, r12)
    1777      5706306 :             denom1 = 1.0_dp - rsst1**2/(d12**2*d23**2); denom2 = 1.0_dp - rsst2**2/(d23**2*d31**2)
    1778      5706306 :             denom3 = 1.0_dp - rsst3**2/(d31**2*d12**2)
    1779      5706306 :             denom1 = SIGN(1.0_dp, denom1)*MAX(ABS(denom1), lindh_denom_floor)
    1780      5706306 :             denom2 = SIGN(1.0_dp, denom2)*MAX(ABS(denom2), lindh_denom_floor)
    1781      5706306 :             denom3 = SIGN(1.0_dp, denom3)*MAX(ABS(denom3), lindh_denom_floor)
    1782      5706306 :             D_mat(1, 1) = r23(idr)/(d12*d23) - rsst1*r12(idr)/(d12**3*d23)
    1783      5706306 :             D_mat(2, 1) = -r23(idr)/(d23*d31) + rsst2*r31(idr)/(d23*d31**3)
    1784              :             D_mat(3, 1) = (r31(idr) - r12(idr))/(d31*d12) + rsst3*r31(idr)/(d31**3*d12) - &
    1785      5706306 :                           rsst3*r12(idr)/(d31*d12**3)
    1786      5706306 :             IF (jat < i .OR. iat > i) THEN
    1787              :                D_mat(1, 2) = (r12(jdr) - r23(jdr))/(d12*d23) + rsst1*r12(jdr)/(d12**3*d23) - &
    1788      4538790 :                              rsst1*r23(jdr)/(d12*d23**3)
    1789      4538790 :                D_mat(2, 2) = r31(jdr)/(d23*d31) - rsst2*r23(jdr)/(d23**3*d31)
    1790      4538790 :                D_mat(3, 2) = -r31(jdr)/(d31*d12) + rsst3*r12(jdr)/(d31*d12**3)
    1791              :             ELSE
    1792      1167516 :                D_mat(1, 2) = -r12(jdr)/(d12*d23) + rsst1*r23(jdr)/(d12*d23**3)
    1793              :                D_mat(2, 2) = (r23(jdr) - r31(jdr))/(d23*d31) + rsst2*r23(jdr)/(d23**3*d31) - &
    1794      1167516 :                              rsst2*r31(jdr)/(d23*d31**3)
    1795      1167516 :                D_mat(3, 2) = r12(jdr)/(d31*d12) - rsst3*r31(jdr)/(d31**3*d12)
    1796              :             END IF
    1797      5706306 :             IF (ABS(denom1) <= 0.011_dp) D_mat(1, 1) = 0.0_dp
    1798      5706306 :             IF (ABS(denom2) <= 0.011_dp) D_mat(2, 1) = 0.0_dp
    1799      5706306 :             IF (ABS(denom3) <= 0.011_dp) D_mat(3, 1) = 0.0_dp
    1800              : 
    1801              :             deriv = deriv + ka1*D_mat(1, 1)*D_mat(1, 2)/denom1 + &
    1802              :                     ka2*D_mat(2, 1)*D_mat(2, 2)/denom2 + &
    1803      6345666 :                     ka3*D_mat(3, 1)*D_mat(3, 2)/denom3
    1804              :          END DO
    1805              :       END IF
    1806       242217 :       deriv = 0.25_dp*deriv
    1807              : 
    1808       242217 :    END FUNCTION angle_second_deriv
    1809              : 
    1810              : END MODULE bfgs_optimizer
        

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