TDDFPT calculation

xujroman leit... at matcalc.de
Wed Aug 25 10:44:05 CEST 2010


Dear Juerg Hutter,

thank you for your answer.

However, I have found the problem in my cp2k calculation.

I have used the following setting in the DFT-PRINT section.

.
.
.
   &PRINT
      &MO_CUBES
        FILENAME ./MOTEST
        STRIDE 1 1 1
        NLUMO 1
        NHOMO 1
      &END MO_CUBES
      &MO
        EIGENVALUES .TRUE.
        OCCUPATION_NUMBERS .TRUE.
      &END MO
    &END PRINT
.
.
.

This leads to the calculation of only the first unoccupied molecular
orbital. Therefore, I obtained only transitions into this state.
Changing the above section into

.
.
.
   &PRINT
      &MO_CUBES
        WRITE_CUBE .FALSE.
        NLUMO 10
      &END MO_CUBES
      &MO
        EIGENVALUES .TRUE.
        OCCUPATION_NUMBERS .TRUE.
      &END MO
    &END PRINT
.
.
.

solved the problem.

However, I found it not intuitive to specify the number of used
unoccupied orbitals of the TDDFT calculation in the section FORCE_EVAL-
> DFT-> PRINT-> MO_CUBES .
Therefore, I suggest for the next cp2k release a new keyword in the
TDDFPT section which specifies the number of LUMOS or at least a hint
in the manual where the number of LUMOS have to be set.


Cheers,
Roman




On Aug 24, 12:56 pm, Juerg Hutter <hut... at pci.uzh.ch> wrote:
> Hi
>
> cp2k uses the Tamm-Dancoff approximation to TDDFT. This is known
> to give excitations that are often very strongly localized (in MO
> space). Do you have evidence that the result you get is not correct?
>
> regards
>
> Juerg
>
> > Dear cp2k users,
>
> > I have tried to to a TDDFT calculation with cp2k.
> > The input file was as follows:
>
> > &FORCE_EVAL
> >  METHOD Quickstep
> >  STRESS_TENSOR ANALYTICAL
> >  &DFT
> >    EXCITATIONS tddfpt
> >    &TDDFPT
> >     MAX_KV 60
> >     NEV 8
> >     OE_CORR SAOP
> >     REORTHO 2
> >     RES_ETYPE SINGLETS
> >     RESTARTS 5
> >     &XC
> >       &XC_FUNCTIONAL  PBE
> >       &END XC_FUNCTIONAL
> >     &END XC
> >    &END TDDFPT
> >    &PRINT
> >      &MO_CUBES
> >        FILENAME ./MOTEST
> >        STRIDE 1 1 1
> >        NLUMO 1
> >        NHOMO 1
> >      &END MO_CUBES
> >      &MO
> >        EIGENVALUES .TRUE.
> >        OCCUPATION_NUMBERS .TRUE.
> >      &END MO
> >    &END PRINT
> >    &POISSON
> >      PERIODIC NONE
> >      POISSON_SOLVER MULTIPOLE
> >      &MULTIPOLE
> >        ANALYTICAL_GTERM .TRUE.
> >        RCUT 8.0
> >      &END MULTIPOLE
> >    &END POISSON
> >    &MGRID
> >      CUTOFF $i
> >      REL_CUTOFF 100
> >    &END MGRID    &QS
> >      WF_INTERPOLATION PS
> >      EXTRAPOLATION_ORDER 3
> >    &END QS
> >    &SCF
> >      SCF_GUESS ATOMIC
> >      ADDED_MOS 11
> >      MAX_SCF 500
> >    &END SCF
> >    &XC
> >      &XC_FUNCTIONAL PBE
> >      &END XC_FUNCTIONAL
> >    &END XC
> >  &END DFT
> >  &SUBSYS
> >    &CELL
> >       PERIODIC NONE
> >         A 16 0 0
> >         B 0 16 0
> >         C 0 0 16
> >    &END CELL
> >   &COORD
> >  C         0.0000015548        1.3995049822        0.0000112361
> >  C         1.2105571712        0.6993498626       -0.0000011831
> >  C         1.2105625355       -0.6993566874       -0.0000046545
> >  C         0.0000152421       -1.3995045587       -0.0000022992
> >  C        -1.2105874557       -0.6993739468        0.0000097107
> >  C        -1.2105811121        0.6993813716        0.0000137609
> >  F        -0.0000016621        2.7455352497       -0.0000018655
> >  F        -2.3775341687        1.3700043040        0.0000017066
> >  F        -2.3775319035       -1.3700126878       -0.0000055826
> >  F        -0.0000018753       -2.7455346120       -0.0000011244
> >  F         2.3775445180       -1.3700080734        0.0000004072
> >  F         2.3775535520        1.3700123130       -0.0000037231
> >    &END COORD
> >    &KIND C
> >      BASIS_SET DZVP-MOLOPT-SR-GTH
> >      POTENTIAL GTH-PBE-q4
> >    &END KIND
> >    &KIND F
> >      BASIS_SET DZVP-MOLOPT-SR-GTH
> >      POTENTIAL GTH-PBE-q7
> >    &END KIND
> >  &END SUBSYS
> > &END FORCE_EVAL
> > &GLOBAL
> >  PROJECT SINGLE-C6F6
> >  RUN_TYPE SPECTRA
> >  PRINT_LEVEL MEDIUM
> > &END GLOBAL
> > &MOTION
> >  &GEO_OPT
> >  OPTIMIZER CG
> >   &CG
> >     &LINE_SEARCH
> >       TYPE 2PNT
> >     &END LINE_SEARCH
> >   &END CG
> >  &END GEO_OPT
> > &END MOTION
>
> > As output for the excited states I obtained the following:
>
> >  excited state :   1            5.205378
>
> >                   33 -> 34             0.693        0.480
> >                   32 -> 34             0.082        0.487
> >                   20 -> 34             0.109        0.499
>
> >  excited state :   2            7.547600
>
> >                   33 -> 34             0.108        0.012
> >                   32 -> 34             0.973        0.959
> >                   21 -> 34             0.149        0.982
>
> >  excited state :   3            7.785291
>
> >                   33 -> 34             0.671        0.450
> >                   32 -> 34             0.070        0.455
> >                   31 -> 34             0.066        0.459
> >                   20 -> 34             0.065        0.464
>
> >  excited state :   4            8.544974
>
> >                   31 -> 34             0.962        0.928
> >                   19 -> 34             0.228        0.980
>
> >  excited state :   5            8.663582
>
> >                   30 -> 34             0.977        0.954
> >                   13 -> 34             0.207        0.997
>
> >  excited state :   6            9.602348
>
> >                   29 -> 34             0.059        0.004
> >                   28 -> 34             0.986        0.976
> >                   18 -> 34             0.084        0.984
> >                   11 -> 34             0.114        0.997
>
> >  excited state :   7            9.771548
>
> >                   29 -> 34             0.983        0.967
> >                   28 -> 34             0.060        0.971
> >                   17 -> 34             0.102        0.981
> >                   10 -> 34             0.126        0.997
>
> >  excited state :   8           10.868760
>
> >                   27 -> 34             1.000        0.999
>
> >  TDDFPT : CheckSum  =  0.899094E+00
>
> > Now my question are:
>
> > Why there are only excitations to the first unoccupied orbital (34)
> > and no contributions higher orbitals (e.g. 35, 36 etc.) ?
>
> > Do I have to specify the number of unoccupied orbitals used in the
> > TDDFT section?
>
> > If, yes, where do have to specify this?
>
> > Sincerely,
> > Roman
>
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>


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