===== Excited states =====

Input file for real time propagation of formaldehyde.

This file will excite the formaldehyde using an impulse (''delta kick'') then propagate the system in time.

The file ch2o_pbe_rtp-output-moments.dat should contain the system dipole moment at each time step.

By extracting the z component of this moment and taking a discrete fourier transform of it (xmgrace maybe) you should be able to obtain the optical absorption spectrum of formaldehyde at PBE level.

<code cp2k input.inp>
&GLOBAL
  PROJECT ch2o_pbe_rtp
  RUN_TYPE rt_propagation
  PRINT_LEVEL low
&END GLOBAL

&FORCE_EVAL
  METHOD Quickstep

  &DFT
    BASIS_SET_FILE_NAME GTH_BASIS_SETS
    POTENTIAL_FILE_NAME POTENTIAL

    &MGRID
      CUTOFF 400
    &END MGRID

    &QS
      METHOD gpw
    &END QS

    &SCF
      MAX_SCF   30
      EPS_SCF   1e-7
      SCF_GUESS atomic
    &END SCF

    &POISSON
       PERIODIC none
       POISSON_SOLVER wavelet
    &END POISSON

    &XC
      &XC_FUNCTIONAL pbe
      &END XC_FUNCTIONAL
    &END XC
    
       &REAL_TIME_PROPAGATION
      INITIAL_WFN SCF_WFN
      EXP_ACCURACY 1E-15
      EPS_ITER 1E-5
      MAX_ITER 100
      DELTA_PULSE_DIRECTION 0 0 1

    &END REAL_TIME_PROPAGATION

    &PRINT
      &MOMENTS LOW
         ADD_LAST NUMERIC
         FILENAME output
         PERIODIC .FALSE.
         COMMON_ITERATION_LEVELS 5
      &END MOMENTS
      &MULLIKEN MEDIUM
      &END MULLIKEN
    &END PRINT

  &END DFT

  &SUBSYS
    &TOPOLOGY
       &CENTER_COORDINATES
       &END CENTER_COORDINATES
    &END TOPOLOGY

    &CELL
      ABC 9.0 9.0 9.0
      PERIODIC NONE
    &END CELL

    &COORD
  O         0.094933   -0.000368    0.895642
  C        -0.031077   -0.000121   -0.307326
  H        -0.090437    0.947608   -0.895642
  H        -0.094933   -0.947608   -0.895562
    &END COORD
    
        &KIND O
      BASIS_SET aug-TZV2P-GTH
      POTENTIAL GTH-PBE-q6
    &END KIND
    &KIND C
      BASIS_SET aug-TZV2P-GTH
      POTENTIAL GTH-PBE-q4
    &END KIND
    &KIND H
      BASIS_SET aug-TZV2P-GTH
      POTENTIAL GTH-PBE-q1
    &END KIND
  &END SUBSYS
&END FORCE_EVAL

&MOTION
  &MD
    ENSEMBLE NVE
    STEPS 20000
    TIMESTEP 0.025
    TEMPERATURE 300.0
  &END MD
&END MOTION
</code>

Here is an input that calculates the first five excited states of formaldehyde using TDDFPT instead. The energies should be the same as for RTP.

//Note that this needs a very up to date CP2K executable to work version > r17219//

<code cp2k input_tddfpt.inp>
&GLOBAL
  PROJECT ch2o_pbe_rks_s_tddfpt
  RUN_TYPE energy
  PRINT_LEVEL low
&END GLOBAL

&FORCE_EVAL
  METHOD Quickstep

  &PROPERTIES
    &TDDFPT
       NSTATES      5
       MAX_ITER    10
       CONVERGENCE [eV] 1.0e-3
    &END TDDFPT
  &END PROPERTIES

  &DFT
    BASIS_SET_FILE_NAME GTH_BASIS_SETS
    POTENTIAL_FILE_NAME POTENTIAL

    &MGRID
      CUTOFF 400
    &END MGRID

    &QS
      METHOD gpw
    &END QS

    &SCF
      MAX_SCF   30
      EPS_SCF   1e-7
      SCF_GUESS atomic
    &END SCF

    &POISSON
       PERIODIC none
       POISSON_SOLVER wavelet
    &END POISSON

    &XC
      &XC_FUNCTIONAL pbe
      &END XC_FUNCTIONAL

      &XC_GRID
        XC_DERIV SPLINE2_SMOOTH
      &END XC_GRID
    &END XC
  &END DFT

  &SUBSYS
    &TOPOLOGY
       &CENTER_COORDINATES
       &END CENTER_COORDINATES
    &END TOPOLOGY

    &CELL
      ABC 9.0 9.0 9.0
      PERIODIC NONE
    &END CELL

    &COORD
  O         0.094933   -0.000368    0.895642
  C        -0.031077   -0.000121   -0.307326
  H        -0.090437    0.947608   -0.895642
  H        -0.094933   -0.947608   -0.895562
    &END COORD

    &KIND O
      BASIS_SET aug-TZV2P-GTH
      POTENTIAL GTH-PBE-q6
    &END KIND
    &KIND C
      BASIS_SET aug-TZV2P-GTH
      POTENTIAL GTH-PBE-q4
    &END KIND
    &KIND H
      BASIS_SET aug-TZV2P-GTH
      POTENTIAL GTH-PBE-q1
    &END KIND
  &END SUBSYS
&END FORCE_EVAL

</code>