LCOV - code coverage report
Current view: top level - src - mp2_grids.F (source / functions) Coverage Total Hit
Test: CP2K Regtests (git:71c3ab0) Lines: 92.3 % 530 489
Test Date: 2026-07-25 06:35:44 Functions: 94.1 % 17 16

            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 to calculate frequency and time grids (integration points and weights)
      10              : !>        for correlation methods
      11              : !> \par History
      12              : !>      05.2019 Refactored from rpa_ri_gpw [Frederick Stein]
      13              : ! **************************************************************************************************
      14              : MODULE mp2_grids
      15              :    USE cp_fm_types,                     ONLY: cp_fm_get_info,&
      16              :                                               cp_fm_type
      17              :    USE greenx_interface,                ONLY: greenx_get_minimax_grid
      18              :    USE input_section_types,             ONLY: section_vals_type,&
      19              :                                               section_vals_val_set
      20              :    USE kinds,                           ONLY: dp
      21              :    USE kpoint_types,                    ONLY: get_kpoint_info,&
      22              :                                               kpoint_env_type,&
      23              :                                               kpoint_type
      24              :    USE machine,                         ONLY: m_flush
      25              :    USE mathconstants,                   ONLY: pi
      26              :    USE message_passing,                 ONLY: mp_para_env_release,&
      27              :                                               mp_para_env_type
      28              :    USE minimax_exp,                     ONLY: get_exp_minimax_coeff
      29              :    USE minimax_exp_gw,                  ONLY: get_exp_minimax_coeff_gw
      30              :    USE minimax_rpa,                     ONLY: get_rpa_minimax_coeff,&
      31              :                                               get_rpa_minimax_coeff_larger_grid
      32              :    USE qs_environment_types,            ONLY: get_qs_env,&
      33              :                                               qs_environment_type
      34              :    USE qs_mo_types,                     ONLY: get_mo_set,&
      35              :                                               mo_set_type
      36              : #include "./base/base_uses.f90"
      37              : 
      38              :    IMPLICIT NONE
      39              : 
      40              :    PRIVATE
      41              : 
      42              :    CHARACTER(len=*), PARAMETER, PRIVATE :: moduleN = 'mp2_grids'
      43              : 
      44              :    PUBLIC :: get_minimax_grid, get_clenshaw_grid, test_least_square_ft, get_l_sq_wghts_cos_tf_t_to_w, &
      45              :              get_l_sq_wghts_cos_tf_w_to_t, get_l_sq_wghts_sin_tf_t_to_w
      46              : 
      47              : CONTAINS
      48              : 
      49              : ! **************************************************************************************************
      50              : !> \brief ...
      51              : !> \param para_env ...
      52              : !> \param unit_nr ...
      53              : !> \param homo ...
      54              : !> \param Eigenval ...
      55              : !> \param num_integ_points ...
      56              : !> \param do_im_time ...
      57              : !> \param do_ri_sos_laplace_mp2 ...
      58              : !> \param do_print ...
      59              : !> \param tau_tj ...
      60              : !> \param tau_wj ...
      61              : !> \param qs_env ...
      62              : !> \param do_gw_im_time ...
      63              : !> \param do_kpoints_cubic_RPA ...
      64              : !> \param e_fermi ...
      65              : !> \param tj ...
      66              : !> \param wj ...
      67              : !> \param weights_cos_tf_t_to_w ...
      68              : !> \param weights_cos_tf_w_to_t ...
      69              : !> \param weights_sin_tf_t_to_w ...
      70              : !> \param regularization ...
      71              : ! **************************************************************************************************
      72          206 :    SUBROUTINE get_minimax_grid(para_env, unit_nr, homo, Eigenval, num_integ_points, &
      73              :                                do_im_time, do_ri_sos_laplace_mp2, do_print, tau_tj, tau_wj, qs_env, do_gw_im_time, &
      74              :                                do_kpoints_cubic_RPA, e_fermi, tj, wj, weights_cos_tf_t_to_w, &
      75              :                                weights_cos_tf_w_to_t, weights_sin_tf_t_to_w, regularization)
      76              : 
      77              :       TYPE(mp_para_env_type), INTENT(IN)                 :: para_env
      78              :       INTEGER, INTENT(IN)                                :: unit_nr
      79              :       INTEGER, DIMENSION(:), INTENT(IN)                  :: homo
      80              :       REAL(KIND=dp), DIMENSION(:, :, :), INTENT(IN)      :: Eigenval
      81              :       INTEGER, INTENT(IN)                                :: num_integ_points
      82              :       LOGICAL, INTENT(IN)                                :: do_im_time, do_ri_sos_laplace_mp2, &
      83              :                                                             do_print
      84              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
      85              :          INTENT(OUT)                                     :: tau_tj, tau_wj
      86              :       TYPE(qs_environment_type), POINTER                 :: qs_env
      87              :       LOGICAL, INTENT(IN)                                :: do_gw_im_time, do_kpoints_cubic_RPA
      88              :       REAL(KIND=dp), INTENT(OUT)                         :: e_fermi
      89              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
      90              :          INTENT(OUT)                                     :: tj, wj
      91              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:, :), &
      92              :          INTENT(OUT)                                     :: weights_cos_tf_t_to_w, &
      93              :                                                             weights_cos_tf_w_to_t, &
      94              :                                                             weights_sin_tf_t_to_w
      95              :       REAL(KIND=dp), INTENT(IN), OPTIONAL                :: regularization
      96              : 
      97              :       CHARACTER(LEN=*), PARAMETER                        :: routineN = 'get_minimax_grid'
      98              :       INTEGER, PARAMETER                                 :: num_points_per_magnitude = 200
      99              : 
     100              :       INTEGER                                            :: handle, ierr, jquad, nspins
     101              :       LOGICAL                                            :: my_do_kpoints
     102              :       REAL(KIND=dp)                                      :: E_Range, Emax, Emin, max_error_min, &
     103              :                                                             my_regularization, scaling
     104          206 :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:)           :: x_tw
     105              : 
     106          206 :       CALL timeset(routineN, handle)
     107              : 
     108              :       CALL determine_energy_range(qs_env, para_env, homo, Eigenval, do_ri_sos_laplace_mp2, &
     109          206 :                                   do_kpoints_cubic_RPA, Emin, Emax, e_range, e_fermi)
     110              : 
     111              :       CALL greenx_get_minimax_grid(unit_nr, num_integ_points, emin, emax, &
     112              :                                    tau_tj, tau_wj, qs_env%mp2_env%ri_g0w0%regularization_minimax, &
     113              :                                    tj, wj, weights_cos_tf_t_to_w, &
     114          206 :                                    weights_cos_tf_w_to_t, weights_sin_tf_t_to_w, ierr)
     115              : 
     116              : ! Shortcut if Greenx was available and successful
     117          206 :       IF (ierr == 0) THEN
     118           76 :          CALL timestop(handle)
     119              :          RETURN
     120              :       END IF
     121              : 
     122              :       ! Test for spin unrestricted
     123          130 :       nspins = SIZE(homo)
     124              : 
     125              :       ! Test whether all necessary variables are available
     126          130 :       my_do_kpoints = .FALSE.
     127          130 :       IF (.NOT. do_ri_sos_laplace_mp2) THEN
     128          130 :          my_do_kpoints = do_kpoints_cubic_RPA
     129              :       END IF
     130              : 
     131              :       my_regularization = 0.0_dp
     132          130 :       IF (PRESENT(regularization)) THEN
     133          130 :          my_regularization = regularization
     134              : 
     135          130 :          IF (num_integ_points > 20 .AND. e_range < 100.0_dp) THEN
     136            0 :             IF (unit_nr > 0) THEN
     137              :                CALL cp_warn(__LOCATION__, &
     138              :                             "You requested a large minimax grid (> 20 points) for a small minimax range R (R < 100). "// &
     139              :                             "That may lead to numerical "// &
     140              :                             "instabilities when computing minimax grid weights. You can prevent small ranges by choosing "// &
     141            0 :                             "a larger basis set with higher angular momenta or alternatively using all-electron calculations.")
     142              :             END IF
     143              :          END IF
     144              : 
     145          130 :          IF (.NOT. do_ri_sos_laplace_mp2) THEN
     146          216 :             ALLOCATE (x_tw(2*num_integ_points))
     147           72 :             x_tw = 0.0_dp
     148           72 :             ierr = 0
     149           72 :             IF (num_integ_points <= 20) THEN
     150           72 :                CALL get_rpa_minimax_coeff(num_integ_points, e_range, x_tw, ierr)
     151              :             ELSE
     152            0 :                CALL get_rpa_minimax_coeff_larger_grid(num_integ_points, e_range, x_tw)
     153              :             END IF
     154              : 
     155          216 :             ALLOCATE (tj(num_integ_points))
     156           72 :             tj = 0.0_dp
     157              : 
     158          144 :             ALLOCATE (wj(num_integ_points))
     159           72 :             wj = 0.0_dp
     160              : 
     161          346 :             DO jquad = 1, num_integ_points
     162          274 :                tj(jquad) = x_tw(jquad)
     163          346 :                wj(jquad) = x_tw(jquad + num_integ_points)
     164              :             END DO
     165              : 
     166              :             ! for the smaller grids, the factor of 4 is included in get_rpa_minimax_coeff for wj
     167           72 :             IF (num_integ_points >= 26) THEN
     168            0 :                wj(:) = wj(:)*4.0_dp
     169              :             END IF
     170              : 
     171           72 :             DEALLOCATE (x_tw)
     172              : 
     173           72 :             IF (unit_nr > 0 .AND. do_print) THEN
     174              :                WRITE (UNIT=unit_nr, FMT="(T3,A,T75,i6)") &
     175           35 :                   "MINIMAX_INFO| Number of integration points:", num_integ_points
     176              :                WRITE (UNIT=unit_nr, FMT="(T3,A,T66,F15.4)") &
     177           35 :                   "MINIMAX_INFO| Gap for the minimax approximation:", Emin
     178              :                WRITE (UNIT=unit_nr, FMT="(T3,A,T66,F15.4)") &
     179           35 :                   "MINIMAX_INFO| Range for the minimax approximation:", e_range
     180           35 :                WRITE (UNIT=unit_nr, FMT="(T3,A,T54,A,T72,A)") "MINIMAX_INFO| Minimax parameters:", "Weights", "Abscissas"
     181          167 :                DO jquad = 1, num_integ_points
     182          167 :                   WRITE (UNIT=unit_nr, FMT="(T41,F20.10,F20.10)") wj(jquad), tj(jquad)
     183              :                END DO
     184           35 :                CALL m_flush(unit_nr)
     185              :             END IF
     186              : 
     187              :             ! scale the minimax parameters
     188          346 :             tj(:) = tj(:)*Emin
     189          346 :             wj(:) = wj(:)*Emin
     190              :          END IF
     191              : 
     192              :          ! set up the minimax time grid
     193          130 :          IF (do_im_time .OR. do_ri_sos_laplace_mp2) THEN
     194              : 
     195          300 :             ALLOCATE (x_tw(2*num_integ_points))
     196          100 :             x_tw = 0.0_dp
     197              : 
     198          100 :             IF (num_integ_points <= 20) THEN
     199          100 :                CALL get_exp_minimax_coeff(num_integ_points, e_range, x_tw)
     200              :             ELSE
     201            0 :                CALL get_exp_minimax_coeff_gw(num_integ_points, e_range, x_tw)
     202              :             END IF
     203              : 
     204              :             ! For RPA we include already a factor of two (see later steps)
     205          100 :             scaling = 2.0_dp
     206          100 :             IF (do_ri_sos_laplace_mp2) scaling = 1.0_dp
     207              : 
     208          300 :             ALLOCATE (tau_tj(num_integ_points))
     209          100 :             tau_tj = 0.0_dp
     210              : 
     211          200 :             ALLOCATE (tau_wj(num_integ_points))
     212          100 :             tau_wj = 0.0_dp
     213              : 
     214          468 :             DO jquad = 1, num_integ_points
     215          368 :                tau_tj(jquad) = x_tw(jquad)/scaling
     216          468 :                tau_wj(jquad) = x_tw(jquad + num_integ_points)/scaling
     217              :             END DO
     218              : 
     219          100 :             DEALLOCATE (x_tw)
     220              : 
     221          100 :             IF (unit_nr > 0 .AND. do_print) THEN
     222              :                WRITE (UNIT=unit_nr, FMT="(T3,A,T66,F15.4)") &
     223           49 :                   "MINIMAX_INFO| Range for the minimax approximation:", e_range
     224              :                ! For testing the gap
     225              :                WRITE (UNIT=unit_nr, FMT="(T3,A,T66,F15.4)") &
     226           49 :                   "MINIMAX_INFO| Gap:", Emin
     227              :                WRITE (UNIT=unit_nr, FMT="(T3,A,T54,A,T72,A)") &
     228           49 :                   "MINIMAX_INFO| Minimax parameters of the time grid:", "Weights", "Abscissas"
     229          228 :                DO jquad = 1, num_integ_points
     230          228 :                   WRITE (UNIT=unit_nr, FMT="(T41,F20.10,F20.10)") tau_wj(jquad), tau_tj(jquad)
     231              :                END DO
     232           49 :                CALL m_flush(unit_nr)
     233              :             END IF
     234              : 
     235              :             ! scale grid from [1,R] to [Emin,Emax]
     236          468 :             tau_tj(:) = tau_tj(:)/Emin
     237          468 :             tau_wj(:) = tau_wj(:)/Emin
     238              : 
     239          100 :             IF (.NOT. do_ri_sos_laplace_mp2) THEN
     240          168 :                ALLOCATE (weights_cos_tf_t_to_w(num_integ_points, num_integ_points))
     241           42 :                weights_cos_tf_t_to_w = 0.0_dp
     242              : 
     243              :                CALL get_l_sq_wghts_cos_tf_t_to_w(num_integ_points, tau_tj, weights_cos_tf_t_to_w, tj, &
     244              :                                                  Emin, Emax, max_error_min, num_points_per_magnitude, &
     245           42 :                                                  my_regularization)
     246              : 
     247              :                ! get the weights for the cosine transform W^c(iw) -> W^c(it)
     248          126 :                ALLOCATE (weights_cos_tf_w_to_t(num_integ_points, num_integ_points))
     249           42 :                weights_cos_tf_w_to_t = 0.0_dp
     250              : 
     251              :                CALL get_l_sq_wghts_cos_tf_w_to_t(num_integ_points, tau_tj, weights_cos_tf_w_to_t, tj, &
     252              :                                                  Emin, Emax, max_error_min, num_points_per_magnitude, &
     253           42 :                                                  my_regularization)
     254              : 
     255           42 :                IF (do_gw_im_time) THEN
     256              : 
     257              :                   ! get the weights for the sine transform Sigma^sin(it) -> Sigma^sin(iw) (PRB 94, 165109 (2016), Eq. 71)
     258           30 :                   ALLOCATE (weights_sin_tf_t_to_w(num_integ_points, num_integ_points))
     259           10 :                   weights_sin_tf_t_to_w = 0.0_dp
     260              : 
     261              :                   CALL get_l_sq_wghts_sin_tf_t_to_w(num_integ_points, tau_tj, weights_sin_tf_t_to_w, tj, &
     262              :                                                     Emin, Emax, max_error_min, num_points_per_magnitude, &
     263           10 :                                                     my_regularization)
     264              : 
     265           10 :                   IF (unit_nr > 0) THEN
     266              :                      WRITE (UNIT=unit_nr, FMT="(T3,A,T66,ES15.2)") &
     267            5 :                         "MINIMAX_INFO| Maximum deviation of the imag. time fit:", max_error_min
     268              :                   END IF
     269              :                END IF
     270              : 
     271              :             END IF
     272              : 
     273              :          END IF
     274              :       END IF
     275              : 
     276          130 :       CALL timestop(handle)
     277              : 
     278          130 :    END SUBROUTINE get_minimax_grid
     279              : 
     280              : ! **************************************************************************************************
     281              : !> \brief ...
     282              : !> \param para_env ...
     283              : !> \param para_env_RPA ...
     284              : !> \param unit_nr ...
     285              : !> \param homo ...
     286              : !> \param virtual ...
     287              : !> \param Eigenval ...
     288              : !> \param num_integ_points ...
     289              : !> \param num_integ_group ...
     290              : !> \param color_rpa_group ...
     291              : !> \param fm_mat_S ...
     292              : !> \param my_do_gw ...
     293              : !> \param ext_scaling ...
     294              : !> \param a_scaling ...
     295              : !> \param tj ...
     296              : !> \param wj ...
     297              : ! **************************************************************************************************
     298          100 :    SUBROUTINE get_clenshaw_grid(para_env, para_env_RPA, unit_nr, homo, virtual, Eigenval, num_integ_points, &
     299          100 :                                 num_integ_group, color_rpa_group, fm_mat_S, my_do_gw, &
     300              :                                 ext_scaling, a_scaling, tj, wj)
     301              : 
     302              :       TYPE(mp_para_env_type), INTENT(IN)                 :: para_env, para_env_RPA
     303              :       INTEGER, INTENT(IN)                                :: unit_nr
     304              :       INTEGER, DIMENSION(:), INTENT(IN)                  :: homo, virtual
     305              :       REAL(KIND=dp), DIMENSION(:, :, :), INTENT(IN)      :: Eigenval
     306              :       INTEGER, INTENT(IN)                                :: num_integ_points, num_integ_group, &
     307              :                                                             color_rpa_group
     308              :       TYPE(cp_fm_type), DIMENSION(:), INTENT(IN)         :: fm_mat_S
     309              :       LOGICAL, INTENT(IN)                                :: my_do_gw
     310              :       REAL(KIND=dp), INTENT(IN)                          :: ext_scaling
     311              :       REAL(KIND=dp), INTENT(OUT)                         :: a_scaling
     312              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
     313              :          INTENT(OUT)                                     :: tj, wj
     314              : 
     315              :       CHARACTER(LEN=*), PARAMETER                        :: routineN = 'get_clenshaw_grid'
     316              : 
     317              :       INTEGER                                            :: handle, jquad, nspins
     318              :       LOGICAL                                            :: my_open_shell
     319              : 
     320          100 :       CALL timeset(routineN, handle)
     321              : 
     322          100 :       nspins = SIZE(homo)
     323          100 :       my_open_shell = (nspins == 2)
     324              : 
     325              :       ! Now, start to prepare the different grid
     326          300 :       ALLOCATE (tj(num_integ_points))
     327          100 :       tj = 0.0_dp
     328              : 
     329          200 :       ALLOCATE (wj(num_integ_points))
     330          100 :       wj = 0.0_dp
     331              : 
     332         4070 :       DO jquad = 1, num_integ_points - 1
     333         3970 :          tj(jquad) = jquad*pi/(2.0_dp*num_integ_points)
     334         4070 :          wj(jquad) = pi/(num_integ_points*SIN(tj(jquad))**2)
     335              :       END DO
     336          100 :       tj(num_integ_points) = pi/2.0_dp
     337          100 :       wj(num_integ_points) = pi/(2.0_dp*num_integ_points*SIN(tj(num_integ_points))**2)
     338              : 
     339          100 :       IF (my_do_gw .AND. ext_scaling > 0.0_dp) THEN
     340           62 :          a_scaling = ext_scaling
     341              :       ELSE
     342              :          CALL calc_scaling_factor(a_scaling, para_env, para_env_RPA, homo, virtual, Eigenval, &
     343              :                                   num_integ_points, num_integ_group, color_rpa_group, &
     344           38 :                                   tj, wj, fm_mat_S)
     345              :       END IF
     346              : 
     347          100 :       IF (unit_nr > 0) WRITE (unit_nr, '(T3,A,T56,F25.5)') 'INTEG_INFO| Scaling parameter:', a_scaling
     348              : 
     349         4170 :       wj(:) = wj(:)*a_scaling
     350              : 
     351          100 :       CALL timestop(handle)
     352              : 
     353          100 :    END SUBROUTINE get_clenshaw_grid
     354              : 
     355              : ! **************************************************************************************************
     356              : !> \brief ...
     357              : !> \param a_scaling_ext ...
     358              : !> \param para_env ...
     359              : !> \param para_env_RPA ...
     360              : !> \param homo ...
     361              : !> \param virtual ...
     362              : !> \param Eigenval ...
     363              : !> \param num_integ_points ...
     364              : !> \param num_integ_group ...
     365              : !> \param color_rpa_group ...
     366              : !> \param tj_ext ...
     367              : !> \param wj_ext ...
     368              : !> \param fm_mat_S ...
     369              : ! **************************************************************************************************
     370           38 :    SUBROUTINE calc_scaling_factor(a_scaling_ext, para_env, para_env_RPA, homo, virtual, Eigenval, &
     371              :                                   num_integ_points, num_integ_group, color_rpa_group, &
     372           38 :                                   tj_ext, wj_ext, fm_mat_S)
     373              :       REAL(KIND=dp), INTENT(OUT)                         :: a_scaling_ext
     374              :       TYPE(mp_para_env_type), INTENT(IN)                 :: para_env, para_env_RPA
     375              :       INTEGER, DIMENSION(:), INTENT(IN)                  :: homo, virtual
     376              :       REAL(KIND=dp), DIMENSION(:, :, :), INTENT(IN)      :: Eigenval
     377              :       INTEGER, INTENT(IN)                                :: num_integ_points, num_integ_group, &
     378              :                                                             color_rpa_group
     379              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
     380              :          INTENT(IN)                                      :: tj_ext, wj_ext
     381              :       TYPE(cp_fm_type), DIMENSION(:), INTENT(IN)         :: fm_mat_S
     382              : 
     383              :       CHARACTER(LEN=*), PARAMETER :: routineN = 'calc_scaling_factor'
     384              : 
     385              :       INTEGER                                            :: handle, icycle, jquad, ncol_local, &
     386              :                                                             ncol_local_beta, nspins
     387              :       LOGICAL                                            :: my_open_shell
     388              :       REAL(KIND=dp) :: a_high, a_low, a_scaling, conv_param, eps, first_deriv, left_term, &
     389              :          right_term, right_term_ref, right_term_ref_beta, step
     390           38 :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:)           :: cottj, D_ia, D_ia_beta, iaia_RI, &
     391           38 :                                                             iaia_RI_beta, M_ia, M_ia_beta
     392              :       TYPE(mp_para_env_type), POINTER                    :: para_env_col, para_env_col_beta
     393              : 
     394           38 :       CALL timeset(routineN, handle)
     395              : 
     396           38 :       nspins = SIZE(homo)
     397           38 :       my_open_shell = (nspins == 2)
     398              : 
     399           38 :       eps = 1.0E-10_dp
     400              : 
     401          114 :       ALLOCATE (cottj(num_integ_points))
     402              : 
     403              :       ! calculate the cotangent of the abscissa tj
     404          488 :       DO jquad = 1, num_integ_points
     405          488 :          cottj(jquad) = 1.0_dp/TAN(tj_ext(jquad))
     406              :       END DO
     407              : 
     408              :       CALL calc_ia_ia_integrals(para_env_RPA, homo(1), virtual(1), ncol_local, right_term_ref, Eigenval(:, 1, 1), &
     409           38 :                                 D_ia, iaia_RI, M_ia, fm_mat_S(1), para_env_col)
     410              : 
     411              :       ! In the open shell case do point 1-2-3 for the beta spin
     412           38 :       IF (my_open_shell) THEN
     413              :          CALL calc_ia_ia_integrals(para_env_RPA, homo(2), virtual(2), ncol_local_beta, right_term_ref_beta, Eigenval(:, 1, 2), &
     414            8 :                                    D_ia_beta, iaia_RI_beta, M_ia_beta, fm_mat_S(2), para_env_col_beta)
     415              : 
     416            8 :          right_term_ref = right_term_ref + right_term_ref_beta
     417              :       END IF
     418              : 
     419              :       ! bcast the result
     420           38 :       IF (para_env%mepos == 0) THEN
     421           19 :          CALL para_env%bcast(right_term_ref, 0)
     422              :       ELSE
     423           19 :          right_term_ref = 0.0_dp
     424           19 :          CALL para_env%bcast(right_term_ref, 0)
     425              :       END IF
     426              : 
     427              :       ! 5) start iteration for solving the non-linear equation by bisection
     428              :       ! find limit, here step=0.5 seems a good compromise
     429           38 :       conv_param = 100.0_dp*EPSILON(right_term_ref)
     430           38 :       step = 0.5_dp
     431           38 :       a_low = 0.0_dp
     432           38 :       a_high = step
     433           38 :       right_term = -right_term_ref
     434          100 :       DO icycle = 1, num_integ_points*2
     435           92 :          a_scaling = a_high
     436              : 
     437              :          CALL calculate_objfunc(a_scaling, left_term, first_deriv, num_integ_points, my_open_shell, &
     438              :                                 M_ia, cottj, wj_ext, D_ia, D_ia_beta, M_ia_beta, &
     439              :                                 ncol_local, ncol_local_beta, num_integ_group, color_rpa_group, &
     440           92 :                                 para_env, para_env_col, para_env_col_beta)
     441           92 :          left_term = left_term/4.0_dp/pi*a_scaling
     442              : 
     443           92 :          IF (ABS(left_term) > ABS(right_term) .OR. ABS(left_term + right_term) <= conv_param) EXIT
     444           62 :          a_low = a_high
     445          100 :          a_high = a_high + step
     446              : 
     447              :       END DO
     448              : 
     449           38 :       IF (ABS(left_term + right_term) >= conv_param) THEN
     450           32 :          IF (a_scaling >= 2*num_integ_points*step) THEN
     451           10 :             a_scaling = 1.0_dp
     452              :          ELSE
     453              : 
     454          340 :             DO icycle = 1, num_integ_points*2
     455          336 :                a_scaling = (a_low + a_high)/2.0_dp
     456              : 
     457              :                CALL calculate_objfunc(a_scaling, left_term, first_deriv, num_integ_points, my_open_shell, &
     458              :                                       M_ia, cottj, wj_ext, D_ia, D_ia_beta, M_ia_beta, &
     459              :                                       ncol_local, ncol_local_beta, num_integ_group, color_rpa_group, &
     460          336 :                                       para_env, para_env_col, para_env_col_beta)
     461          336 :                left_term = left_term/4.0_dp/pi*a_scaling
     462              : 
     463          336 :                IF (ABS(left_term) > ABS(right_term)) THEN
     464              :                   a_high = a_scaling
     465              :                ELSE
     466          186 :                   a_low = a_scaling
     467              :                END IF
     468              : 
     469          340 :                IF (ABS(a_high - a_low) < 1.0e-5_dp) EXIT
     470              : 
     471              :             END DO
     472              : 
     473              :          END IF
     474              :       END IF
     475              : 
     476           38 :       a_scaling_ext = a_scaling
     477           38 :       CALL para_env%bcast(a_scaling_ext, 0)
     478              : 
     479           38 :       DEALLOCATE (cottj)
     480           38 :       DEALLOCATE (iaia_RI)
     481           38 :       DEALLOCATE (D_ia)
     482           38 :       DEALLOCATE (M_ia)
     483           38 :       CALL mp_para_env_release(para_env_col)
     484              : 
     485           38 :       IF (my_open_shell) THEN
     486            8 :          DEALLOCATE (iaia_RI_beta)
     487            8 :          DEALLOCATE (D_ia_beta)
     488            8 :          DEALLOCATE (M_ia_beta)
     489            8 :          CALL mp_para_env_release(para_env_col_beta)
     490              :       END IF
     491              : 
     492           38 :       CALL timestop(handle)
     493              : 
     494           76 :    END SUBROUTINE calc_scaling_factor
     495              : 
     496              : ! **************************************************************************************************
     497              : !> \brief ...
     498              : !> \param para_env_RPA ...
     499              : !> \param homo ...
     500              : !> \param virtual ...
     501              : !> \param ncol_local ...
     502              : !> \param right_term_ref ...
     503              : !> \param Eigenval ...
     504              : !> \param D_ia ...
     505              : !> \param iaia_RI ...
     506              : !> \param M_ia ...
     507              : !> \param fm_mat_S ...
     508              : !> \param para_env_col ...
     509              : ! **************************************************************************************************
     510           46 :    SUBROUTINE calc_ia_ia_integrals(para_env_RPA, homo, virtual, ncol_local, right_term_ref, Eigenval, &
     511              :                                    D_ia, iaia_RI, M_ia, fm_mat_S, para_env_col)
     512              : 
     513              :       TYPE(mp_para_env_type), INTENT(IN)                 :: para_env_RPA
     514              :       INTEGER, INTENT(IN)                                :: homo, virtual
     515              :       INTEGER, INTENT(OUT)                               :: ncol_local
     516              :       REAL(KIND=dp), INTENT(OUT)                         :: right_term_ref
     517              :       REAL(KIND=dp), DIMENSION(:), INTENT(IN)            :: Eigenval
     518              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
     519              :          INTENT(OUT)                                     :: D_ia, iaia_RI, M_ia
     520              :       TYPE(cp_fm_type), INTENT(IN)                       :: fm_mat_S
     521              :       TYPE(mp_para_env_type), POINTER                    :: para_env_col
     522              : 
     523              :       CHARACTER(LEN=*), PARAMETER :: routineN = 'calc_ia_ia_integrals'
     524              : 
     525              :       INTEGER                                            :: avirt, color_col, color_row, handle, &
     526              :                                                             i_global, iiB, iocc, nrow_local
     527           46 :       INTEGER, DIMENSION(:), POINTER                     :: col_indices, row_indices
     528              :       REAL(KIND=dp)                                      :: eigen_diff
     529              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:)           :: iaia_RI_dp
     530              :       TYPE(mp_para_env_type), POINTER                    :: para_env_row
     531              : 
     532           46 :       CALL timeset(routineN, handle)
     533              : 
     534              :       ! calculate the (ia|ia) RI integrals
     535              :       ! ----------------------------------
     536              :       ! 1) get info fm_mat_S
     537              :       CALL cp_fm_get_info(matrix=fm_mat_S, &
     538              :                           nrow_local=nrow_local, &
     539              :                           ncol_local=ncol_local, &
     540              :                           row_indices=row_indices, &
     541           46 :                           col_indices=col_indices)
     542              : 
     543              :       ! allocate the local buffer of iaia_RI integrals (dp kind)
     544          136 :       ALLOCATE (iaia_RI_dp(ncol_local))
     545           46 :       iaia_RI_dp = 0.0_dp
     546              : 
     547              :       ! 2) perform the local multiplication SUM_K (ia|K)*(ia|K)
     548         2764 :       DO iiB = 1, ncol_local
     549       188006 :          iaia_RI_dp(iiB) = iaia_RI_dp(iiB) + DOT_PRODUCT(fm_mat_S%local_data(:, iiB), fm_mat_S%local_data(:, iiB))
     550              :       END DO
     551              : 
     552              :       ! 3) sum the result with the processes of the RPA_group having the same columns
     553              :       !          _______ia______               _
     554              :       !         |   |   |   |   |             | |
     555              :       !     --> | 1 | 5 | 9 | 13|   SUM -->   | |
     556              :       !         |___|__ |___|___|             |_|
     557              :       !         |   |   |   |   |             | |
     558              :       !     --> | 2 | 6 | 10| 14|   SUM -->   | |
     559              :       !       K |___|___|___|___|             |_|   (ia|ia)_RI
     560              :       !         |   |   |   |   |             | |
     561              :       !     --> | 3 | 7 | 11| 15|   SUM -->   | |
     562              :       !         |___|___|___|___|             |_|
     563              :       !         |   |   |   |   |             | |
     564              :       !     --> | 4 | 8 | 12| 16|   SUM -->   | |
     565              :       !         |___|___|___|___|             |_|
     566              :       !
     567              : 
     568           46 :       color_col = fm_mat_S%matrix_struct%context%mepos(2)
     569           46 :       ALLOCATE (para_env_col)
     570           46 :       CALL para_env_col%from_split(para_env_RPA, color_col)
     571              : 
     572           46 :       CALL para_env_col%sum(iaia_RI_dp)
     573              : 
     574              :       ! convert the iaia_RI_dp into double-double precision
     575          136 :       ALLOCATE (iaia_RI(ncol_local))
     576         2764 :       DO iiB = 1, ncol_local
     577         2764 :          iaia_RI(iiB) = iaia_RI_dp(iiB)
     578              :       END DO
     579           46 :       DEALLOCATE (iaia_RI_dp)
     580              : 
     581              :       ! 4) calculate the right hand term, D_ia is the matrix containing the
     582              :       ! orbital energy differences, M_ia is the diagonal of the full RPA 'excitation'
     583              :       ! matrix
     584          136 :       ALLOCATE (D_ia(ncol_local))
     585              : 
     586           90 :       ALLOCATE (M_ia(ncol_local))
     587              : 
     588         2764 :       DO iiB = 1, ncol_local
     589         2718 :          i_global = col_indices(iiB)
     590              : 
     591         2718 :          iocc = MAX(1, i_global - 1)/virtual + 1
     592         2718 :          avirt = i_global - (iocc - 1)*virtual
     593         2718 :          eigen_diff = Eigenval(avirt + homo) - Eigenval(iocc)
     594              : 
     595         2764 :          D_ia(iiB) = eigen_diff
     596              :       END DO
     597              : 
     598         2764 :       DO iiB = 1, ncol_local
     599         2764 :          M_ia(iiB) = D_ia(iiB)*D_ia(iiB) + 2.0_dp*D_ia(iiB)*iaia_RI(iiB)
     600              :       END DO
     601              : 
     602           46 :       right_term_ref = 0.0_dp
     603         2764 :       DO iiB = 1, ncol_local
     604         2764 :          right_term_ref = right_term_ref + (SQRT(M_ia(iiB)) - D_ia(iiB) - iaia_RI(iiB))
     605              :       END DO
     606           46 :       right_term_ref = right_term_ref/2.0_dp
     607              : 
     608              :       ! sum the result with the processes of the RPA_group having the same row
     609           46 :       color_row = fm_mat_S%matrix_struct%context%mepos(1)
     610           46 :       ALLOCATE (para_env_row)
     611           46 :       CALL para_env_row%from_split(para_env_RPA, color_row)
     612              : 
     613              :       ! allocate communication array for rows
     614           46 :       CALL para_env_row%sum(right_term_ref)
     615              : 
     616           46 :       CALL mp_para_env_release(para_env_row)
     617              : 
     618           46 :       CALL timestop(handle)
     619              : 
     620           46 :    END SUBROUTINE calc_ia_ia_integrals
     621              : 
     622              : ! **************************************************************************************************
     623              : !> \brief ...
     624              : !> \param a_scaling ...
     625              : !> \param left_term ...
     626              : !> \param first_deriv ...
     627              : !> \param num_integ_points ...
     628              : !> \param my_open_shell ...
     629              : !> \param M_ia ...
     630              : !> \param cottj ...
     631              : !> \param wj ...
     632              : !> \param D_ia ...
     633              : !> \param D_ia_beta ...
     634              : !> \param M_ia_beta ...
     635              : !> \param ncol_local ...
     636              : !> \param ncol_local_beta ...
     637              : !> \param num_integ_group ...
     638              : !> \param color_rpa_group ...
     639              : !> \param para_env ...
     640              : !> \param para_env_col ...
     641              : !> \param para_env_col_beta ...
     642              : ! **************************************************************************************************
     643          428 :    SUBROUTINE calculate_objfunc(a_scaling, left_term, first_deriv, num_integ_points, my_open_shell, &
     644              :                                 M_ia, cottj, wj, D_ia, D_ia_beta, M_ia_beta, &
     645              :                                 ncol_local, ncol_local_beta, num_integ_group, color_rpa_group, &
     646              :                                 para_env, para_env_col, para_env_col_beta)
     647              :       REAL(KIND=dp), INTENT(IN)                          :: a_scaling
     648              :       REAL(KIND=dp), INTENT(INOUT)                       :: left_term, first_deriv
     649              :       INTEGER, INTENT(IN)                                :: num_integ_points
     650              :       LOGICAL, INTENT(IN)                                :: my_open_shell
     651              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
     652              :          INTENT(IN)                                      :: M_ia, cottj, wj, D_ia, D_ia_beta, &
     653              :                                                             M_ia_beta
     654              :       INTEGER, INTENT(IN)                                :: ncol_local, ncol_local_beta, &
     655              :                                                             num_integ_group, color_rpa_group
     656              :       TYPE(mp_para_env_type), INTENT(IN)                 :: para_env, para_env_col
     657              :       TYPE(mp_para_env_type), POINTER                    :: para_env_col_beta
     658              : 
     659              :       INTEGER                                            :: iiB, jquad
     660              :       REAL(KIND=dp)                                      :: first_deriv_beta, left_term_beta, omega
     661              : 
     662          428 :       left_term = 0.0_dp
     663          428 :       first_deriv = 0.0_dp
     664          428 :       left_term_beta = 0.0_dp
     665          428 :       first_deriv_beta = 0.0_dp
     666         4452 :       DO jquad = 1, num_integ_points
     667              :          ! parallelize over integration points
     668         4024 :          IF (MODULO(jquad, num_integ_group) /= color_rpa_group) CYCLE
     669         2212 :          omega = a_scaling*cottj(jquad)
     670              : 
     671       162484 :          DO iiB = 1, ncol_local
     672              :             ! parallelize over ia elements in the para_env_row group
     673       160272 :             IF (MODULO(iiB, para_env_col%num_pe) /= para_env_col%mepos) CYCLE
     674              :             ! calculate left_term
     675              :             left_term = left_term + wj(jquad)* &
     676              :                         (LOG(1.0_dp + (M_ia(iiB) - D_ia(iiB)**2)/(omega**2 + D_ia(iiB)**2)) - &
     677       145072 :                          (M_ia(iiB) - D_ia(iiB)**2)/(omega**2 + D_ia(iiB)**2))
     678              :             first_deriv = first_deriv + wj(jquad)*cottj(jquad)**2* &
     679       162484 :                           ((-M_ia(iiB) + D_ia(iiB)**2)**2/((omega**2 + D_ia(iiB)**2)**2*(omega**2 + M_ia(iiB))))
     680              :          END DO
     681              : 
     682         2640 :          IF (my_open_shell) THEN
     683        14490 :             DO iiB = 1, ncol_local_beta
     684              :                ! parallelize over ia elements in the para_env_row group
     685        14140 :                IF (MODULO(iiB, para_env_col_beta%num_pe) /= para_env_col_beta%mepos) CYCLE
     686              :                ! calculate left_term
     687              :                left_term_beta = left_term_beta + wj(jquad)* &
     688              :                                 (LOG(1.0_dp + (M_ia_beta(iiB) - D_ia_beta(iiB)**2)/(omega**2 + D_ia_beta(iiB)**2)) - &
     689        14140 :                                  (M_ia_beta(iiB) - D_ia_beta(iiB)**2)/(omega**2 + D_ia_beta(iiB)**2))
     690              :                first_deriv_beta = &
     691              :                   first_deriv_beta + wj(jquad)*cottj(jquad)**2* &
     692        14490 :                   ((-M_ia_beta(iiB) + D_ia_beta(iiB)**2)**2/((omega**2 + D_ia_beta(iiB)**2)**2*(omega**2 + M_ia_beta(iiB))))
     693              :             END DO
     694              :          END IF
     695              : 
     696              :       END DO
     697              : 
     698              :       ! sum the contribution from all proc, starting form the row group
     699          428 :       CALL para_env%sum(left_term)
     700          428 :       CALL para_env%sum(first_deriv)
     701              : 
     702          428 :       IF (my_open_shell) THEN
     703           70 :          CALL para_env%sum(left_term_beta)
     704           70 :          CALL para_env%sum(first_deriv_beta)
     705              : 
     706           70 :          left_term = left_term + left_term_beta
     707           70 :          first_deriv = first_deriv + first_deriv_beta
     708              :       END IF
     709              : 
     710          428 :    END SUBROUTINE calculate_objfunc
     711              : 
     712              : ! **************************************************************************************************
     713              : !> \brief Calculate integration weights for the tau grid (in dependency of the omega node)
     714              : !> \param num_integ_points ...
     715              : !> \param tau_tj ...
     716              : !> \param weights_cos_tf_t_to_w ...
     717              : !> \param omega_tj ...
     718              : !> \param E_min ...
     719              : !> \param E_max ...
     720              : !> \param max_error ...
     721              : !> \param num_points_per_magnitude ...
     722              : !> \param regularization ...
     723              : ! **************************************************************************************************
     724           94 :    SUBROUTINE get_l_sq_wghts_cos_tf_t_to_w(num_integ_points, tau_tj, weights_cos_tf_t_to_w, omega_tj, &
     725              :                                            E_min, E_max, max_error, num_points_per_magnitude, &
     726              :                                            regularization)
     727              : 
     728              :       INTEGER, INTENT(IN)                                :: num_integ_points
     729              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
     730              :          INTENT(IN)                                      :: tau_tj
     731              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:, :), &
     732              :          INTENT(INOUT)                                   :: weights_cos_tf_t_to_w
     733              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
     734              :          INTENT(IN)                                      :: omega_tj
     735              :       REAL(KIND=dp), INTENT(IN)                          :: E_min, E_max
     736              :       REAL(KIND=dp), INTENT(INOUT)                       :: max_error
     737              :       INTEGER, INTENT(IN)                                :: num_points_per_magnitude
     738              :       REAL(KIND=dp), INTENT(IN)                          :: regularization
     739              : 
     740              :       CHARACTER(LEN=*), PARAMETER :: routineN = 'get_l_sq_wghts_cos_tf_t_to_w'
     741              : 
     742              :       INTEGER                                            :: handle, iii, info, jjj, jquad, lwork, &
     743              :                                                             num_x_nodes
     744           94 :       INTEGER, ALLOCATABLE, DIMENSION(:)                 :: iwork
     745              :       REAL(KIND=dp)                                      :: multiplicator, omega
     746           94 :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:)           :: sing_values, tau_wj_work, vec_UTy, work, &
     747              :                                                             x_values, y_values
     748           94 :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:, :)        :: mat_A, mat_SinvVSinvSigma, &
     749           94 :                                                             mat_SinvVSinvT, mat_U
     750              : 
     751           94 :       CALL timeset(routineN, handle)
     752              : 
     753              :       ! take num_points_per_magnitude points per 10-interval
     754           94 :       num_x_nodes = (INT(LOG10(E_max/E_min)) + 1)*num_points_per_magnitude
     755              : 
     756              :       ! take at least as many x points as integration points to have clear
     757              :       ! input for the singular value decomposition
     758           94 :       num_x_nodes = MAX(num_x_nodes, num_integ_points)
     759              : 
     760          282 :       ALLOCATE (x_values(num_x_nodes))
     761           94 :       x_values = 0.0_dp
     762          188 :       ALLOCATE (y_values(num_x_nodes))
     763           94 :       y_values = 0.0_dp
     764          376 :       ALLOCATE (mat_A(num_x_nodes, num_integ_points))
     765           94 :       mat_A = 0.0_dp
     766          282 :       ALLOCATE (tau_wj_work(num_integ_points))
     767           94 :       tau_wj_work = 0.0_dp
     768          188 :       ALLOCATE (sing_values(num_integ_points))
     769           94 :       sing_values = 0.0_dp
     770          376 :       ALLOCATE (mat_U(num_x_nodes, num_x_nodes))
     771           94 :       mat_U = 0.0_dp
     772          282 :       ALLOCATE (mat_SinvVSinvT(num_x_nodes, num_integ_points))
     773              : 
     774           94 :       mat_SinvVSinvT = 0.0_dp
     775              :       ! double the value nessary for 'A' to achieve good performance
     776           94 :       lwork = 8*num_integ_points*num_integ_points + 12*num_integ_points + 2*num_x_nodes
     777          282 :       ALLOCATE (work(lwork))
     778           94 :       work = 0.0_dp
     779          282 :       ALLOCATE (iwork(8*num_integ_points))
     780           94 :       iwork = 0
     781          282 :       ALLOCATE (mat_SinvVSinvSigma(num_integ_points, num_x_nodes))
     782           94 :       mat_SinvVSinvSigma = 0.0_dp
     783          188 :       ALLOCATE (vec_UTy(num_x_nodes))
     784           94 :       vec_UTy = 0.0_dp
     785              : 
     786           94 :       max_error = 0.0_dp
     787              : 
     788              :       ! loop over all omega frequency points
     789          830 :       DO jquad = 1, num_integ_points
     790              : 
     791              :          ! set the x-values logarithmically in the interval [Emin,Emax]
     792          736 :          multiplicator = (E_max/E_min)**(1.0_dp/(REAL(num_x_nodes, KIND=dp) - 1.0_dp))
     793       235136 :          DO iii = 1, num_x_nodes
     794       235136 :             x_values(iii) = E_min*multiplicator**(iii - 1)
     795              :          END DO
     796              : 
     797          736 :          omega = omega_tj(jquad)
     798              : 
     799              :          ! y=2x/(x^2+omega_k^2)
     800       235136 :          DO iii = 1, num_x_nodes
     801       235136 :             y_values(iii) = 2.0_dp*x_values(iii)/((x_values(iii))**2 + omega**2)
     802              :          END DO
     803              : 
     804              :          ! calculate mat_A
     805         9732 :          DO jjj = 1, num_integ_points
     806      2477732 :             DO iii = 1, num_x_nodes
     807      2476996 :                mat_A(iii, jjj) = COS(omega*tau_tj(jjj))*EXP(-x_values(iii)*tau_tj(jjj))
     808              :             END DO
     809              :          END DO
     810              : 
     811              :          ! Singular value decomposition of mat_A
     812              :          CALL DGESDD('A', num_x_nodes, num_integ_points, mat_A, num_x_nodes, sing_values, mat_U, num_x_nodes, &
     813          736 :                      mat_SinvVSinvT, num_x_nodes, work, lwork, iwork, info)
     814              : 
     815          736 :          CPASSERT(info == 0)
     816              : 
     817              :          ! integration weights = V Sigma U^T y
     818              :          ! 1) V*Sigma
     819         9732 :          DO jjj = 1, num_integ_points
     820       152332 :             DO iii = 1, num_integ_points
     821              : !               mat_SinvVSinvSigma(iii, jjj) = mat_SinvVSinvT(jjj, iii)/sing_values(jjj)
     822              :                mat_SinvVSinvSigma(iii, jjj) = mat_SinvVSinvT(jjj, iii)*sing_values(jjj) &
     823       151596 :                                               /(regularization**2 + sing_values(jjj)**2)
     824              :             END DO
     825              :          END DO
     826              : 
     827              :          ! 2) U^T y
     828              :          CALL DGEMM('T', 'N', num_x_nodes, 1, num_x_nodes, 1.0_dp, mat_U, num_x_nodes, y_values, num_x_nodes, &
     829          736 :                     0.0_dp, vec_UTy, num_x_nodes)
     830              : 
     831              :          ! 3) (V*Sigma) * (U^T y)
     832              :          CALL DGEMM('N', 'N', num_integ_points, 1, num_x_nodes, 1.0_dp, mat_SinvVSinvSigma, num_integ_points, vec_UTy, &
     833          736 :                     num_x_nodes, 0.0_dp, tau_wj_work, num_integ_points)
     834              : 
     835         9732 :          weights_cos_tf_t_to_w(jquad, :) = tau_wj_work(:)
     836              : 
     837              :          CALL calc_max_error_fit_tau_grid_with_cosine(max_error, omega, tau_tj, tau_wj_work, x_values, &
     838          830 :                                                       y_values, num_integ_points, num_x_nodes)
     839              : 
     840              :       END DO ! jquad
     841              : 
     842            0 :       DEALLOCATE (x_values, y_values, mat_A, tau_wj_work, sing_values, mat_U, mat_SinvVSinvT, &
     843           94 :                   work, iwork, mat_SinvVSinvSigma, vec_UTy)
     844              : 
     845           94 :       CALL timestop(handle)
     846              : 
     847           94 :    END SUBROUTINE get_l_sq_wghts_cos_tf_t_to_w
     848              : 
     849              : ! **************************************************************************************************
     850              : !> \brief Calculate integration weights for the tau grid (in dependency of the omega node)
     851              : !> \param num_integ_points ...
     852              : !> \param tau_tj ...
     853              : !> \param weights_sin_tf_t_to_w ...
     854              : !> \param omega_tj ...
     855              : !> \param E_min ...
     856              : !> \param E_max ...
     857              : !> \param max_error ...
     858              : !> \param num_points_per_magnitude ...
     859              : !> \param regularization ...
     860              : ! **************************************************************************************************
     861           62 :    SUBROUTINE get_l_sq_wghts_sin_tf_t_to_w(num_integ_points, tau_tj, weights_sin_tf_t_to_w, omega_tj, &
     862              :                                            E_min, E_max, max_error, num_points_per_magnitude, regularization)
     863              : 
     864              :       INTEGER, INTENT(IN)                                :: num_integ_points
     865              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
     866              :          INTENT(IN)                                      :: tau_tj
     867              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:, :), &
     868              :          INTENT(INOUT)                                   :: weights_sin_tf_t_to_w
     869              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
     870              :          INTENT(IN)                                      :: omega_tj
     871              :       REAL(KIND=dp), INTENT(IN)                          :: E_min, E_max
     872              :       REAL(KIND=dp), INTENT(OUT)                         :: max_error
     873              :       INTEGER, INTENT(IN)                                :: num_points_per_magnitude
     874              :       REAL(KIND=dp), INTENT(IN)                          :: regularization
     875              : 
     876              :       CHARACTER(LEN=*), PARAMETER :: routineN = 'get_l_sq_wghts_sin_tf_t_to_w'
     877              : 
     878              :       INTEGER                                            :: handle, iii, info, jjj, jquad, lwork, &
     879              :                                                             num_x_nodes
     880           62 :       INTEGER, ALLOCATABLE, DIMENSION(:)                 :: iwork
     881              :       REAL(KIND=dp)                                      :: chi2_min_jquad, multiplicator, omega
     882           62 :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:)           :: sing_values, tau_wj_work, vec_UTy, work, &
     883           62 :                                                             work_array, x_values, y_values
     884           62 :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:, :)        :: mat_A, mat_SinvVSinvSigma, &
     885           62 :                                                             mat_SinvVSinvT, mat_U
     886              : 
     887           62 :       CALL timeset(routineN, handle)
     888              : 
     889              :       ! take num_points_per_magnitude points per 10-interval
     890           62 :       num_x_nodes = (INT(LOG10(E_max/E_min)) + 1)*num_points_per_magnitude
     891              : 
     892              :       ! take at least as many x points as integration points to have clear
     893              :       ! input for the singular value decomposition
     894           62 :       num_x_nodes = MAX(num_x_nodes, num_integ_points)
     895              : 
     896          186 :       ALLOCATE (x_values(num_x_nodes))
     897           62 :       x_values = 0.0_dp
     898          124 :       ALLOCATE (y_values(num_x_nodes))
     899           62 :       y_values = 0.0_dp
     900          248 :       ALLOCATE (mat_A(num_x_nodes, num_integ_points))
     901           62 :       mat_A = 0.0_dp
     902          186 :       ALLOCATE (tau_wj_work(num_integ_points))
     903           62 :       tau_wj_work = 0.0_dp
     904          186 :       ALLOCATE (work_array(2*num_integ_points))
     905              :       work_array = 0.0_dp
     906          124 :       ALLOCATE (sing_values(num_integ_points))
     907           62 :       sing_values = 0.0_dp
     908          248 :       ALLOCATE (mat_U(num_x_nodes, num_x_nodes))
     909           62 :       mat_U = 0.0_dp
     910          186 :       ALLOCATE (mat_SinvVSinvT(num_x_nodes, num_integ_points))
     911              : 
     912           62 :       mat_SinvVSinvT = 0.0_dp
     913              :       ! double the value nessary for 'A' to achieve good performance
     914           62 :       lwork = 8*num_integ_points*num_integ_points + 12*num_integ_points + 2*num_x_nodes
     915          186 :       ALLOCATE (work(lwork))
     916           62 :       work = 0.0_dp
     917          186 :       ALLOCATE (iwork(8*num_integ_points))
     918           62 :       iwork = 0
     919          186 :       ALLOCATE (mat_SinvVSinvSigma(num_integ_points, num_x_nodes))
     920           62 :       mat_SinvVSinvSigma = 0.0_dp
     921          124 :       ALLOCATE (vec_UTy(num_x_nodes))
     922           62 :       vec_UTy = 0.0_dp
     923              : 
     924           62 :       max_error = 0.0_dp
     925              : 
     926              :       ! loop over all omega frequency points
     927          710 :       DO jquad = 1, num_integ_points
     928              : 
     929          648 :          chi2_min_jquad = 100.0_dp
     930              : 
     931              :          ! set the x-values logarithmically in the interval [Emin,Emax]
     932          648 :          multiplicator = (E_max/E_min)**(1.0_dp/(REAL(num_x_nodes, KIND=dp) - 1.0_dp))
     933       203848 :          DO iii = 1, num_x_nodes
     934       203848 :             x_values(iii) = E_min*multiplicator**(iii - 1)
     935              :          END DO
     936              : 
     937          648 :          omega = omega_tj(jquad)
     938              : 
     939              :          ! y=2x/(x^2+omega_k^2)
     940       203848 :          DO iii = 1, num_x_nodes
     941              : !            y_values(iii) = 2.0_dp*x_values(iii)/((x_values(iii))**2+omega**2)
     942       203848 :             y_values(iii) = 2.0_dp*omega/((x_values(iii))**2 + omega**2)
     943              :          END DO
     944              : 
     945              :          ! calculate mat_A
     946         9396 :          DO jjj = 1, num_integ_points
     947      2388596 :             DO iii = 1, num_x_nodes
     948      2387948 :                mat_A(iii, jjj) = SIN(omega*tau_tj(jjj))*EXP(-x_values(iii)*tau_tj(jjj))
     949              :             END DO
     950              :          END DO
     951              : 
     952              :          ! Singular value decomposition of mat_A
     953              :          CALL DGESDD('A', num_x_nodes, num_integ_points, mat_A, num_x_nodes, sing_values, mat_U, num_x_nodes, &
     954          648 :                      mat_SinvVSinvT, num_x_nodes, work, lwork, iwork, info)
     955              : 
     956          648 :          CPASSERT(info == 0)
     957              : 
     958              :          ! integration weights = V Sigma U^T y
     959              :          ! 1) V*Sigma
     960         9396 :          DO jjj = 1, num_integ_points
     961       151284 :             DO iii = 1, num_integ_points
     962              : !               mat_SinvVSinvSigma(iii, jjj) = mat_SinvVSinvT(jjj, iii)/sing_values(jjj)
     963              :                mat_SinvVSinvSigma(iii, jjj) = mat_SinvVSinvT(jjj, iii)*sing_values(jjj) &
     964       150636 :                                               /(regularization**2 + sing_values(jjj)**2)
     965              :             END DO
     966              :          END DO
     967              : 
     968              :          ! 2) U^T y
     969              :          CALL DGEMM('T', 'N', num_x_nodes, 1, num_x_nodes, 1.0_dp, mat_U, num_x_nodes, y_values, num_x_nodes, &
     970          648 :                     0.0_dp, vec_UTy, num_x_nodes)
     971              : 
     972              :          ! 3) (V*Sigma) * (U^T y)
     973              :          CALL DGEMM('N', 'N', num_integ_points, 1, num_x_nodes, 1.0_dp, mat_SinvVSinvSigma, num_integ_points, vec_UTy, &
     974          648 :                     num_x_nodes, 0.0_dp, tau_wj_work, num_integ_points)
     975              : 
     976         9396 :          weights_sin_tf_t_to_w(jquad, :) = tau_wj_work(:)
     977              : 
     978              :          CALL calc_max_error_fit_tau_grid_with_sine(max_error, omega, tau_tj, tau_wj_work, x_values, &
     979          710 :                                                     y_values, num_integ_points, num_x_nodes)
     980              : 
     981              :       END DO ! jquad
     982              : 
     983            0 :       DEALLOCATE (x_values, y_values, mat_A, tau_wj_work, work_array, sing_values, mat_U, mat_SinvVSinvT, &
     984           62 :                   work, iwork, mat_SinvVSinvSigma, vec_UTy)
     985              : 
     986           62 :       CALL timestop(handle)
     987              : 
     988           62 :    END SUBROUTINE get_l_sq_wghts_sin_tf_t_to_w
     989              : 
     990              : ! **************************************************************************************************
     991              : !> \brief ...
     992              : !> \param max_error ...
     993              : !> \param omega ...
     994              : !> \param tau_tj ...
     995              : !> \param tau_wj_work ...
     996              : !> \param x_values ...
     997              : !> \param y_values ...
     998              : !> \param num_integ_points ...
     999              : !> \param num_x_nodes ...
    1000              : ! **************************************************************************************************
    1001          736 :    PURE SUBROUTINE calc_max_error_fit_tau_grid_with_cosine(max_error, omega, tau_tj, tau_wj_work, x_values, &
    1002              :                                                            y_values, num_integ_points, num_x_nodes)
    1003              : 
    1004              :       REAL(KIND=dp), INTENT(INOUT)                       :: max_error, omega
    1005              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
    1006              :          INTENT(IN)                                      :: tau_tj, tau_wj_work, x_values, y_values
    1007              :       INTEGER, INTENT(IN)                                :: num_integ_points, num_x_nodes
    1008              : 
    1009              :       INTEGER                                            :: kkk
    1010              :       REAL(KIND=dp)                                      :: func_val, func_val_temp, max_error_tmp
    1011              : 
    1012          736 :       max_error_tmp = 0.0_dp
    1013              : 
    1014       235136 :       DO kkk = 1, num_x_nodes
    1015              : 
    1016              :          func_val = 0.0_dp
    1017              : 
    1018       234400 :          CALL eval_fit_func_tau_grid_cosine(func_val, x_values(kkk), num_integ_points, tau_tj, tau_wj_work, omega)
    1019              : 
    1020       235136 :          IF (ABS(y_values(kkk) - func_val) > max_error_tmp) THEN
    1021              :             max_error_tmp = ABS(y_values(kkk) - func_val)
    1022              :             func_val_temp = func_val
    1023              :          END IF
    1024              : 
    1025              :       END DO
    1026              : 
    1027          736 :       IF (max_error_tmp > max_error) THEN
    1028              : 
    1029          196 :          max_error = max_error_tmp
    1030              : 
    1031              :       END IF
    1032              : 
    1033          736 :    END SUBROUTINE calc_max_error_fit_tau_grid_with_cosine
    1034              : 
    1035              : ! **************************************************************************************************
    1036              : !> \brief Evaluate fit function when calculating tau grid for cosine transform
    1037              : !> \param func_val ...
    1038              : !> \param x_value ...
    1039              : !> \param num_integ_points ...
    1040              : !> \param tau_tj ...
    1041              : !> \param tau_wj_work ...
    1042              : !> \param omega ...
    1043              : ! **************************************************************************************************
    1044       234400 :    PURE SUBROUTINE eval_fit_func_tau_grid_cosine(func_val, x_value, num_integ_points, tau_tj, tau_wj_work, omega)
    1045              : 
    1046              :       REAL(KIND=dp), INTENT(OUT)                         :: func_val
    1047              :       REAL(KIND=dp), INTENT(IN)                          :: x_value
    1048              :       INTEGER, INTENT(IN)                                :: num_integ_points
    1049              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
    1050              :          INTENT(IN)                                      :: tau_tj, tau_wj_work
    1051              :       REAL(KIND=dp), INTENT(IN)                          :: omega
    1052              : 
    1053              :       INTEGER                                            :: iii
    1054              : 
    1055       234400 :       func_val = 0.0_dp
    1056              : 
    1057      2702400 :       DO iii = 1, num_integ_points
    1058              : 
    1059              :          ! calculate value of the fit function
    1060      2702400 :          func_val = func_val + tau_wj_work(iii)*COS(omega*tau_tj(iii))*EXP(-x_value*tau_tj(iii))
    1061              : 
    1062              :       END DO
    1063              : 
    1064       234400 :    END SUBROUTINE eval_fit_func_tau_grid_cosine
    1065              : 
    1066              : ! **************************************************************************************************
    1067              : !> \brief Evaluate fit function when calculating tau grid for sine transform
    1068              : !> \param func_val ...
    1069              : !> \param x_value ...
    1070              : !> \param num_integ_points ...
    1071              : !> \param tau_tj ...
    1072              : !> \param tau_wj_work ...
    1073              : !> \param omega ...
    1074              : ! **************************************************************************************************
    1075       203200 :    PURE SUBROUTINE eval_fit_func_tau_grid_sine(func_val, x_value, num_integ_points, tau_tj, tau_wj_work, omega)
    1076              : 
    1077              :       REAL(KIND=dp), INTENT(INOUT)                       :: func_val
    1078              :       REAL(KIND=dp), INTENT(IN)                          :: x_value
    1079              :       INTEGER, INTENT(in)                                :: num_integ_points
    1080              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
    1081              :          INTENT(IN)                                      :: tau_tj, tau_wj_work
    1082              :       REAL(KIND=dp), INTENT(IN)                          :: omega
    1083              : 
    1084              :       INTEGER                                            :: iii
    1085              : 
    1086       203200 :       func_val = 0.0_dp
    1087              : 
    1088      2582400 :       DO iii = 1, num_integ_points
    1089              : 
    1090              :          ! calculate value of the fit function
    1091      2582400 :          func_val = func_val + tau_wj_work(iii)*SIN(omega*tau_tj(iii))*EXP(-x_value*tau_tj(iii))
    1092              : 
    1093              :       END DO
    1094              : 
    1095       203200 :    END SUBROUTINE eval_fit_func_tau_grid_sine
    1096              : 
    1097              : ! **************************************************************************************************
    1098              : !> \brief ...
    1099              : !> \param max_error ...
    1100              : !> \param omega ...
    1101              : !> \param tau_tj ...
    1102              : !> \param tau_wj_work ...
    1103              : !> \param x_values ...
    1104              : !> \param y_values ...
    1105              : !> \param num_integ_points ...
    1106              : !> \param num_x_nodes ...
    1107              : ! **************************************************************************************************
    1108          648 :    PURE SUBROUTINE calc_max_error_fit_tau_grid_with_sine(max_error, omega, tau_tj, tau_wj_work, x_values, &
    1109              :                                                          y_values, num_integ_points, num_x_nodes)
    1110              : 
    1111              :       REAL(KIND=dp), INTENT(INOUT)                       :: max_error, omega
    1112              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
    1113              :          INTENT(IN)                                      :: tau_tj, tau_wj_work, x_values, y_values
    1114              :       INTEGER, INTENT(IN)                                :: num_integ_points, num_x_nodes
    1115              : 
    1116              :       INTEGER                                            :: kkk
    1117              :       REAL(KIND=dp)                                      :: func_val, func_val_temp, max_error_tmp
    1118              : 
    1119          648 :       max_error_tmp = 0.0_dp
    1120              : 
    1121       203848 :       DO kkk = 1, num_x_nodes
    1122              : 
    1123       203200 :          func_val = 0.0_dp
    1124              : 
    1125       203200 :          CALL eval_fit_func_tau_grid_sine(func_val, x_values(kkk), num_integ_points, tau_tj, tau_wj_work, omega)
    1126              : 
    1127       203848 :          IF (ABS(y_values(kkk) - func_val) > max_error_tmp) THEN
    1128              :             max_error_tmp = ABS(y_values(kkk) - func_val)
    1129              :             func_val_temp = func_val
    1130              :          END IF
    1131              : 
    1132              :       END DO
    1133              : 
    1134          648 :       IF (max_error_tmp > max_error) THEN
    1135              : 
    1136           66 :          max_error = max_error_tmp
    1137              : 
    1138              :       END IF
    1139              : 
    1140          648 :    END SUBROUTINE calc_max_error_fit_tau_grid_with_sine
    1141              : 
    1142              : ! **************************************************************************************************
    1143              : !> \brief test the singular value decomposition for the computation of integration weights for the
    1144              : !>         Fourier transform between time and frequency grid in cubic-scaling RPA
    1145              : !> \param nR ...
    1146              : !> \param iw ...
    1147              : ! **************************************************************************************************
    1148            0 :    SUBROUTINE test_least_square_ft(nR, iw)
    1149              :       INTEGER, INTENT(IN)                                :: nR, iw
    1150              : 
    1151              :       INTEGER                                            :: ierr, iR, jquad, num_integ_points
    1152              :       REAL(KIND=dp)                                      :: max_error, multiplicator, Rc, Rc_max
    1153            0 :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:)           :: tau_tj, tau_wj, tj, wj, x_tw
    1154            0 :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:, :)        :: weights_cos_tf_t_to_w
    1155              : 
    1156            0 :       Rc_max = 1.0E+7
    1157              : 
    1158            0 :       multiplicator = Rc_max**(1.0_dp/(REAL(nR, KIND=dp) - 1.0_dp))
    1159              : 
    1160            0 :       DO num_integ_points = 1, 20
    1161              : 
    1162            0 :          ALLOCATE (x_tw(2*num_integ_points))
    1163            0 :          x_tw = 0.0_dp
    1164            0 :          ALLOCATE (tau_tj(num_integ_points))
    1165            0 :          tau_tj = 0.0_dp
    1166            0 :          ALLOCATE (weights_cos_tf_t_to_w(num_integ_points, num_integ_points))
    1167            0 :          weights_cos_tf_t_to_w = 0.0_dp
    1168            0 :          ALLOCATE (tau_wj(num_integ_points))
    1169              :          tau_wj = 0.0_dp
    1170            0 :          ALLOCATE (tj(num_integ_points))
    1171            0 :          tj = 0.0_dp
    1172            0 :          ALLOCATE (wj(num_integ_points))
    1173              :          wj = 0.0_dp
    1174              : 
    1175            0 :          DO iR = 0, nR - 1
    1176              : 
    1177            0 :             Rc = 2.0_dp*multiplicator**iR
    1178              : 
    1179            0 :             ierr = 0
    1180            0 :             CALL get_rpa_minimax_coeff(num_integ_points, Rc, x_tw, ierr, print_warning=.FALSE.)
    1181              : 
    1182            0 :             DO jquad = 1, num_integ_points
    1183            0 :                tj(jquad) = x_tw(jquad)
    1184            0 :                wj(jquad) = x_tw(jquad + num_integ_points)
    1185              :             END DO
    1186              : 
    1187            0 :             x_tw = 0.0_dp
    1188              : 
    1189            0 :             CALL get_exp_minimax_coeff(num_integ_points, Rc, x_tw)
    1190              : 
    1191            0 :             DO jquad = 1, num_integ_points
    1192            0 :                tau_tj(jquad) = x_tw(jquad)/2.0_dp
    1193            0 :                tau_wj(jquad) = x_tw(jquad + num_integ_points)/2.0_dp
    1194              :             END DO
    1195              : 
    1196              :             CALL get_l_sq_wghts_cos_tf_t_to_w(num_integ_points, tau_tj, &
    1197              :                                               weights_cos_tf_t_to_w, tj, &
    1198            0 :                                               1.0_dp, Rc, max_error, 200, 0.0_dp)
    1199              : 
    1200            0 :             IF (iw > 0) THEN
    1201            0 :                WRITE (iw, '(T2, I3, F12.1, ES12.3)') num_integ_points, Rc, max_error
    1202              :             END IF
    1203              : 
    1204              :          END DO
    1205              : 
    1206            0 :          DEALLOCATE (x_tw, tau_tj, weights_cos_tf_t_to_w, tau_wj, wj, tj)
    1207              : 
    1208              :       END DO
    1209              : 
    1210            0 :    END SUBROUTINE test_least_square_ft
    1211              : 
    1212              : ! **************************************************************************************************
    1213              : !> \brief ...
    1214              : !> \param num_integ_points ...
    1215              : !> \param tau_tj ...
    1216              : !> \param weights_cos_tf_w_to_t ...
    1217              : !> \param omega_tj ...
    1218              : !> \param E_min ...
    1219              : !> \param E_max ...
    1220              : !> \param max_error ...
    1221              : !> \param num_points_per_magnitude ...
    1222              : !> \param regularization ...
    1223              : ! **************************************************************************************************
    1224           94 :    SUBROUTINE get_l_sq_wghts_cos_tf_w_to_t(num_integ_points, tau_tj, weights_cos_tf_w_to_t, omega_tj, &
    1225              :                                            E_min, E_max, max_error, num_points_per_magnitude, regularization)
    1226              : 
    1227              :       INTEGER, INTENT(IN)                                :: num_integ_points
    1228              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
    1229              :          INTENT(IN)                                      :: tau_tj
    1230              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:, :), &
    1231              :          INTENT(INOUT)                                   :: weights_cos_tf_w_to_t
    1232              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
    1233              :          INTENT(IN)                                      :: omega_tj
    1234              :       REAL(KIND=dp), INTENT(IN)                          :: E_min, E_max
    1235              :       REAL(KIND=dp), INTENT(INOUT)                       :: max_error
    1236              :       INTEGER, INTENT(IN)                                :: num_points_per_magnitude
    1237              :       REAL(KIND=dp), INTENT(IN)                          :: regularization
    1238              : 
    1239              :       CHARACTER(LEN=*), PARAMETER :: routineN = 'get_l_sq_wghts_cos_tf_w_to_t'
    1240              : 
    1241              :       INTEGER                                            :: handle, iii, info, jjj, jquad, lwork, &
    1242              :                                                             num_x_nodes
    1243           94 :       INTEGER, ALLOCATABLE, DIMENSION(:)                 :: iwork
    1244              :       REAL(KIND=dp)                                      :: chi2_min_jquad, multiplicator, omega, &
    1245              :                                                             tau, x_value
    1246           94 :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:)           :: omega_wj_work, sing_values, vec_UTy, &
    1247           94 :                                                             work, work_array, x_values, y_values
    1248           94 :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:, :)        :: mat_A, mat_SinvVSinvSigma, &
    1249           94 :                                                             mat_SinvVSinvT, mat_U
    1250              : 
    1251           94 :       CALL timeset(routineN, handle)
    1252              : 
    1253              :       ! take num_points_per_magnitude points per 10-interval
    1254           94 :       num_x_nodes = (INT(LOG10(E_max/E_min)) + 1)*num_points_per_magnitude
    1255              : 
    1256              :       ! take at least as many x points as integration points to have clear
    1257              :       ! input for the singular value decomposition
    1258           94 :       num_x_nodes = MAX(num_x_nodes, num_integ_points)
    1259              : 
    1260          282 :       ALLOCATE (x_values(num_x_nodes))
    1261           94 :       x_values = 0.0_dp
    1262          188 :       ALLOCATE (y_values(num_x_nodes))
    1263           94 :       y_values = 0.0_dp
    1264          376 :       ALLOCATE (mat_A(num_x_nodes, num_integ_points))
    1265           94 :       mat_A = 0.0_dp
    1266          282 :       ALLOCATE (omega_wj_work(num_integ_points))
    1267           94 :       omega_wj_work = 0.0_dp
    1268          282 :       ALLOCATE (work_array(2*num_integ_points))
    1269              :       work_array = 0.0_dp
    1270          188 :       ALLOCATE (sing_values(num_integ_points))
    1271           94 :       sing_values = 0.0_dp
    1272          376 :       ALLOCATE (mat_U(num_x_nodes, num_x_nodes))
    1273           94 :       mat_U = 0.0_dp
    1274          282 :       ALLOCATE (mat_SinvVSinvT(num_x_nodes, num_integ_points))
    1275              : 
    1276           94 :       mat_SinvVSinvT = 0.0_dp
    1277              :       ! double the value nessary for 'A' to achieve good performance
    1278           94 :       lwork = 8*num_integ_points*num_integ_points + 12*num_integ_points + 2*num_x_nodes
    1279          282 :       ALLOCATE (work(lwork))
    1280           94 :       work = 0.0_dp
    1281          282 :       ALLOCATE (iwork(8*num_integ_points))
    1282           94 :       iwork = 0
    1283          282 :       ALLOCATE (mat_SinvVSinvSigma(num_integ_points, num_x_nodes))
    1284           94 :       mat_SinvVSinvSigma = 0.0_dp
    1285          188 :       ALLOCATE (vec_UTy(num_x_nodes))
    1286           94 :       vec_UTy = 0.0_dp
    1287              : 
    1288              :       ! set the x-values logarithmically in the interval [Emin,Emax]
    1289           94 :       multiplicator = (E_max/E_min)**(1.0_dp/(REAL(num_x_nodes, KIND=dp) - 1.0_dp))
    1290        33294 :       DO iii = 1, num_x_nodes
    1291        33294 :          x_values(iii) = E_min*multiplicator**(iii - 1)
    1292              :       END DO
    1293              : 
    1294           94 :       max_error = 0.0_dp
    1295              : 
    1296              :       ! loop over all tau time points
    1297          830 :       DO jquad = 1, num_integ_points
    1298              : 
    1299          736 :          chi2_min_jquad = 100.0_dp
    1300              : 
    1301          736 :          tau = tau_tj(jquad)
    1302              : 
    1303              :          ! y=exp(-x*|tau_k|)
    1304       235136 :          DO iii = 1, num_x_nodes
    1305       235136 :             y_values(iii) = EXP(-x_values(iii)*tau)
    1306              :          END DO
    1307              : 
    1308              :          ! calculate mat_A
    1309         9732 :          DO jjj = 1, num_integ_points
    1310      2477732 :             DO iii = 1, num_x_nodes
    1311      2468000 :                omega = omega_tj(jjj)
    1312      2468000 :                x_value = x_values(iii)
    1313      2476996 :                mat_A(iii, jjj) = COS(tau*omega)*2.0_dp*x_value/(x_value**2 + omega**2)
    1314              :             END DO
    1315              :          END DO
    1316              : 
    1317              :          ! Singular value decomposition of mat_A
    1318              :          CALL DGESDD('A', num_x_nodes, num_integ_points, mat_A, num_x_nodes, sing_values, mat_U, num_x_nodes, &
    1319          736 :                      mat_SinvVSinvT, num_x_nodes, work, lwork, iwork, info)
    1320              : 
    1321          736 :          CPASSERT(info == 0)
    1322              : 
    1323              :          ! integration weights = V Sigma U^T y
    1324              :          ! 1) V*Sigma
    1325         9732 :          DO jjj = 1, num_integ_points
    1326       152332 :             DO iii = 1, num_integ_points
    1327              : !               mat_SinvVSinvSigma(iii, jjj) = mat_SinvVSinvT(jjj, iii)/sing_values(jjj)
    1328              :                mat_SinvVSinvSigma(iii, jjj) = mat_SinvVSinvT(jjj, iii)*sing_values(jjj) &
    1329       151596 :                                               /(regularization**2 + sing_values(jjj)**2)
    1330              :             END DO
    1331              :          END DO
    1332              : 
    1333              :          ! 2) U^T y
    1334              :          CALL DGEMM('T', 'N', num_x_nodes, 1, num_x_nodes, 1.0_dp, mat_U, num_x_nodes, y_values, num_x_nodes, &
    1335          736 :                     0.0_dp, vec_UTy, num_x_nodes)
    1336              : 
    1337              :          ! 3) (V*Sigma) * (U^T y)
    1338              :          CALL DGEMM('N', 'N', num_integ_points, 1, num_x_nodes, 1.0_dp, mat_SinvVSinvSigma, num_integ_points, vec_UTy, &
    1339          736 :                     num_x_nodes, 0.0_dp, omega_wj_work, num_integ_points)
    1340              : 
    1341         9732 :          weights_cos_tf_w_to_t(jquad, :) = omega_wj_work(:)
    1342              : 
    1343              :          CALL calc_max_error_fit_omega_grid_with_cosine(max_error, tau, omega_tj, omega_wj_work, x_values, &
    1344          830 :                                                         y_values, num_integ_points, num_x_nodes)
    1345              : 
    1346              :       END DO ! jquad
    1347              : 
    1348            0 :       DEALLOCATE (x_values, y_values, mat_A, omega_wj_work, work_array, sing_values, mat_U, mat_SinvVSinvT, &
    1349           94 :                   work, iwork, mat_SinvVSinvSigma, vec_UTy)
    1350              : 
    1351           94 :       CALL timestop(handle)
    1352              : 
    1353           94 :    END SUBROUTINE get_l_sq_wghts_cos_tf_w_to_t
    1354              : 
    1355              : ! **************************************************************************************************
    1356              : !> \brief ...
    1357              : !> \param max_error ...
    1358              : !> \param tau ...
    1359              : !> \param omega_tj ...
    1360              : !> \param omega_wj_work ...
    1361              : !> \param x_values ...
    1362              : !> \param y_values ...
    1363              : !> \param num_integ_points ...
    1364              : !> \param num_x_nodes ...
    1365              : ! **************************************************************************************************
    1366          736 :    SUBROUTINE calc_max_error_fit_omega_grid_with_cosine(max_error, tau, omega_tj, omega_wj_work, x_values, &
    1367              :                                                         y_values, num_integ_points, num_x_nodes)
    1368              : 
    1369              :       REAL(KIND=dp), INTENT(INOUT)                       :: max_error
    1370              :       REAL(KIND=dp), INTENT(IN)                          :: tau
    1371              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
    1372              :          INTENT(IN)                                      :: omega_tj, omega_wj_work, x_values, &
    1373              :                                                             y_values
    1374              :       INTEGER, INTENT(IN)                                :: num_integ_points, num_x_nodes
    1375              : 
    1376              :       CHARACTER(LEN=*), PARAMETER :: routineN = 'calc_max_error_fit_omega_grid_with_cosine'
    1377              : 
    1378              :       INTEGER                                            :: handle, kkk
    1379              :       REAL(KIND=dp)                                      :: func_val, func_val_temp, max_error_tmp
    1380              : 
    1381          736 :       CALL timeset(routineN, handle)
    1382              : 
    1383          736 :       max_error_tmp = 0.0_dp
    1384              : 
    1385       235136 :       DO kkk = 1, num_x_nodes
    1386              : 
    1387              :          func_val = 0.0_dp
    1388              : 
    1389       234400 :          CALL eval_fit_func_omega_grid_cosine(func_val, x_values(kkk), num_integ_points, omega_tj, omega_wj_work, tau)
    1390              : 
    1391       235136 :          IF (ABS(y_values(kkk) - func_val) > max_error_tmp) THEN
    1392              :             max_error_tmp = ABS(y_values(kkk) - func_val)
    1393              :             func_val_temp = func_val
    1394              :          END IF
    1395              : 
    1396              :       END DO
    1397              : 
    1398          736 :       IF (max_error_tmp > max_error) THEN
    1399              : 
    1400          232 :          max_error = max_error_tmp
    1401              : 
    1402              :       END IF
    1403              : 
    1404          736 :       CALL timestop(handle)
    1405              : 
    1406          736 :    END SUBROUTINE calc_max_error_fit_omega_grid_with_cosine
    1407              : 
    1408              : ! **************************************************************************************************
    1409              : !> \brief ...
    1410              : !> \param func_val ...
    1411              : !> \param x_value ...
    1412              : !> \param num_integ_points ...
    1413              : !> \param omega_tj ...
    1414              : !> \param omega_wj_work ...
    1415              : !> \param tau ...
    1416              : ! **************************************************************************************************
    1417       234400 :    PURE SUBROUTINE eval_fit_func_omega_grid_cosine(func_val, x_value, num_integ_points, omega_tj, omega_wj_work, tau)
    1418              :       REAL(KIND=dp), INTENT(OUT)                         :: func_val
    1419              :       REAL(KIND=dp), INTENT(IN)                          :: x_value
    1420              :       INTEGER, INTENT(IN)                                :: num_integ_points
    1421              :       REAL(KIND=dp), ALLOCATABLE, DIMENSION(:), &
    1422              :          INTENT(IN)                                      :: omega_tj, omega_wj_work
    1423              :       REAL(KIND=dp), INTENT(IN)                          :: tau
    1424              : 
    1425              :       INTEGER                                            :: iii
    1426              :       REAL(KIND=dp)                                      :: omega
    1427              : 
    1428       234400 :       func_val = 0.0_dp
    1429              : 
    1430      2702400 :       DO iii = 1, num_integ_points
    1431              : 
    1432              :          ! calculate value of the fit function
    1433      2468000 :          omega = omega_tj(iii)
    1434      2702400 :          func_val = func_val + omega_wj_work(iii)*COS(tau*omega)*2.0_dp*x_value/(x_value**2 + omega**2)
    1435              : 
    1436              :       END DO
    1437              : 
    1438       234400 :    END SUBROUTINE eval_fit_func_omega_grid_cosine
    1439              : 
    1440              : ! **************************************************************************************************
    1441              : !> \brief ...
    1442              : !> \param qs_env ...
    1443              : !> \param para_env ...
    1444              : !> \param gap ...
    1445              : !> \param max_eig_diff ...
    1446              : !> \param e_fermi ...
    1447              : ! **************************************************************************************************
    1448           12 :    SUBROUTINE gap_and_max_eig_diff_kpoints(qs_env, para_env, gap, max_eig_diff, e_fermi)
    1449              : 
    1450              :       TYPE(qs_environment_type), POINTER                 :: qs_env
    1451              :       TYPE(mp_para_env_type), INTENT(IN)                 :: para_env
    1452              :       REAL(KIND=dp), INTENT(OUT)                         :: gap, max_eig_diff, e_fermi
    1453              : 
    1454              :       CHARACTER(LEN=*), PARAMETER :: routineN = 'gap_and_max_eig_diff_kpoints'
    1455              : 
    1456              :       INTEGER                                            :: handle, homo, ikpgr, ispin, kplocal, &
    1457              :                                                             nmo, nspin
    1458              :       INTEGER, DIMENSION(2)                              :: kp_range
    1459              :       REAL(KIND=dp)                                      :: e_homo, e_homo_temp, e_lumo, e_lumo_temp
    1460              :       REAL(KIND=dp), DIMENSION(3)                        :: tmp
    1461            6 :       REAL(KIND=dp), DIMENSION(:), POINTER               :: eigenvalues
    1462              :       TYPE(kpoint_env_type), POINTER                     :: kp
    1463              :       TYPE(kpoint_type), POINTER                         :: kpoint
    1464              :       TYPE(mo_set_type), POINTER                         :: mo_set
    1465              : 
    1466            6 :       CALL timeset(routineN, handle)
    1467              : 
    1468              :       CALL get_qs_env(qs_env, &
    1469            6 :                       kpoints=kpoint)
    1470              : 
    1471            6 :       mo_set => kpoint%kp_env(1)%kpoint_env%mos(1, 1)
    1472            6 :       CALL get_mo_set(mo_set, nmo=nmo)
    1473              : 
    1474            6 :       CALL get_kpoint_info(kpoint, kp_range=kp_range)
    1475            6 :       kplocal = kp_range(2) - kp_range(1) + 1
    1476              : 
    1477            6 :       gap = 1000.0_dp
    1478            6 :       max_eig_diff = 0.0_dp
    1479            6 :       e_homo = -1000.0_dp
    1480            6 :       e_lumo = 1000.0_dp
    1481              : 
    1482           18 :       DO ikpgr = 1, kplocal
    1483           12 :          kp => kpoint%kp_env(ikpgr)%kpoint_env
    1484           12 :          nspin = SIZE(kp%mos, 2)
    1485           30 :          DO ispin = 1, nspin
    1486           12 :             mo_set => kp%mos(1, ispin)
    1487           12 :             CALL get_mo_set(mo_set, eigenvalues=eigenvalues, homo=homo)
    1488           12 :             e_homo_temp = eigenvalues(homo)
    1489           12 :             e_lumo_temp = eigenvalues(homo + 1)
    1490              : 
    1491              :             IF (e_homo_temp > e_homo) e_homo = e_homo_temp
    1492              :             IF (e_lumo_temp < e_lumo) e_lumo = e_lumo_temp
    1493           24 :             IF (eigenvalues(nmo) - eigenvalues(1) > max_eig_diff) max_eig_diff = eigenvalues(nmo) - eigenvalues(1)
    1494              : 
    1495              :          END DO
    1496              :       END DO
    1497              : 
    1498              :       ! Collect all three numbers in an array
    1499              :       ! Reverse sign of lumo to reduce number of MPI calls
    1500            6 :       tmp(1) = e_homo
    1501            6 :       tmp(2) = -e_lumo
    1502            6 :       tmp(3) = max_eig_diff
    1503            6 :       CALL para_env%max(tmp)
    1504              : 
    1505            6 :       gap = -tmp(2) - tmp(1)
    1506            6 :       e_fermi = (tmp(1) - tmp(2))*0.5_dp
    1507            6 :       max_eig_diff = tmp(3)
    1508              : 
    1509            6 :       CALL timestop(handle)
    1510              : 
    1511            6 :    END SUBROUTINE gap_and_max_eig_diff_kpoints
    1512              : 
    1513              : ! **************************************************************************************************
    1514              : !> \brief returns minimal and maximal energy values for the E_range for the minimax grid selection
    1515              : !> \param qs_env ...
    1516              : !> \param para_env ...
    1517              : !> \param homo index of the homo level for the respective spin channel
    1518              : !> \param Eigenval eigenvalues
    1519              : !> \param do_ri_sos_laplace_mp2 flag for SOS-MP2
    1520              : !> \param do_kpoints_cubic_RPA flag for cubic-scaling RPA with k-points
    1521              : !> \param Emin minimal eigenvalue difference (gap of the system)
    1522              : !> \param Emax maximal eigenvalue difference
    1523              : !> \param e_range ...
    1524              : !> \param e_fermi Fermi level
    1525              : ! **************************************************************************************************
    1526          206 :    SUBROUTINE determine_energy_range(qs_env, para_env, homo, Eigenval, do_ri_sos_laplace_mp2, &
    1527              :                                      do_kpoints_cubic_RPA, Emin, Emax, e_range, e_fermi)
    1528              : 
    1529              :       TYPE(qs_environment_type), POINTER                 :: qs_env
    1530              :       TYPE(mp_para_env_type), INTENT(IN)                 :: para_env
    1531              :       INTEGER, DIMENSION(:), INTENT(IN)                  :: homo
    1532              :       REAL(KIND=dp), DIMENSION(:, :, :), INTENT(IN)      :: Eigenval
    1533              :       LOGICAL, INTENT(IN)                                :: do_ri_sos_laplace_mp2, &
    1534              :                                                             do_kpoints_cubic_RPA
    1535              :       REAL(KIND=dp), INTENT(OUT)                         :: Emin, Emax, e_range, e_fermi
    1536              : 
    1537              :       CHARACTER(LEN=*), PARAMETER :: routineN = 'determine_energy_range'
    1538              : 
    1539              :       INTEGER                                            :: handle, ispin, nspins
    1540              :       LOGICAL                                            :: my_do_kpoints
    1541              :       TYPE(section_vals_type), POINTER                   :: input
    1542              : 
    1543          206 :       CALL timeset(routineN, handle)
    1544              :       ! Test for spin unrestricted
    1545          206 :       nspins = SIZE(homo)
    1546              : 
    1547              :       ! Test whether all necessary variables are available
    1548          206 :       my_do_kpoints = .FALSE.
    1549          206 :       IF (.NOT. do_ri_sos_laplace_mp2) THEN
    1550          148 :          my_do_kpoints = do_kpoints_cubic_RPA
    1551              :       END IF
    1552              : 
    1553          148 :       IF (my_do_kpoints) THEN
    1554            6 :          CALL gap_and_max_eig_diff_kpoints(qs_env, para_env, Emin, Emax, e_fermi)
    1555            6 :          E_Range = Emax/Emin
    1556              :       ELSE
    1557          200 :          IF (qs_env%mp2_env%E_range <= 1.0_dp .OR. qs_env%mp2_env%E_gap <= 0.0_dp) THEN
    1558          152 :             Emin = HUGE(dp)
    1559          152 :             Emax = 0.0_dp
    1560          340 :             DO ispin = 1, nspins
    1561          340 :                IF (homo(ispin) > 0) THEN
    1562          184 :                   Emin = MIN(Emin, Eigenval(homo(ispin) + 1, 1, ispin) - Eigenval(homo(ispin), 1, ispin))
    1563        14732 :                   Emax = MAX(Emax, MAXVAL(Eigenval(:, :, ispin)) - MINVAL(Eigenval(:, :, ispin)))
    1564              :                END IF
    1565              :             END DO
    1566          152 :             E_Range = Emax/Emin
    1567          152 :             qs_env%mp2_env%e_range = e_range
    1568          152 :             qs_env%mp2_env%e_gap = Emin
    1569              : 
    1570          152 :             CALL get_qs_env(qs_env, input=input)
    1571          152 :             CALL section_vals_val_set(input, "DFT%XC%WF_CORRELATION%E_RANGE", r_val=e_range)
    1572          152 :             CALL section_vals_val_set(input, "DFT%XC%WF_CORRELATION%E_GAP", r_val=emin)
    1573              :          ELSE
    1574           48 :             E_range = qs_env%mp2_env%E_range
    1575           48 :             Emin = qs_env%mp2_env%E_gap
    1576           48 :             Emax = Emin*E_range
    1577              :          END IF
    1578              :       END IF
    1579              : 
    1580              :       ! When we perform SOS-MP2, we need an additional factor of 2 for the energies (compare with mp2_laplace.F)
    1581              :       ! We do not need weights etc. for the cosine transform
    1582              :       ! We do not scale Emax because it is not needed for SOS-MP2
    1583          206 :       IF (do_ri_sos_laplace_mp2) THEN
    1584           58 :          Emin = Emin*2.0_dp
    1585           58 :          Emax = Emax*2.0_dp
    1586              :       END IF
    1587              : 
    1588          206 :       CALL timestop(handle)
    1589          206 :    END SUBROUTINE determine_energy_range
    1590              : 
    1591              : END MODULE mp2_grids
        

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