[CP2K:2814] TDDFPT calculation

Juerg Hutter hut... at pci.uzh.ch
Tue Aug 24 12:56:05 CEST 2010


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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