ROKS input

[NUCP2K]

Dear Matthias,

  I followed your suggestion on LOW_SPIN_ROKS, and ran geometry
optimization using the input file shown below. The calculation did go
through, but I am not sure if the calculation was on S1 (first singlet
excited state) PES since I have to specify the MULTIPLICITY to be 3
instead of 1 to avoid input errors. What do you think?

  Thank you very much.

Hanning


  &DFT
    ROKS
    MULTIP 3
    &LOW_SPIN_ROKS
       ENERGY_SCALING 2.0 -1.0
       SPIN_CONFIGURATION 1 1
       SPIN_CONFIGURATION 1 2
    &END
    &MGRID
      CUTOFF 100
    &END MGRID
    &QS
      EPS_DEFAULT 1.0E-8
    &END QS
    &SCF
      MAX_SCF 1000
      SCF_GUESS ATOMIC
      &OT
        ROTATION
      &END OT
    &END SCF
    &XC
      &XC_FUNCTIONAL PADE
      &END XC_FUNCTIONAL
    &END XC
  &END DFT
  &SUBSYS
    &CELL
      ABC 6.0 6.0 8.0
    &END CELL
    &COORD
    C         -0.2558206925       -0.0439868417        0.6850619693
    C         -0.2214915625       -0.0386665897       -0.6514432536
    H         -0.4100752923        0.8714166677        1.2581094627
    H         -0.1401850725       -0.9650616559        1.2579495323
    H         -0.0795226532       -0.9560364450       -1.2252531634
    H         -0.3528336094        0.8817708920       -1.2228724740
    &END COORD
    &KIND H
      BASIS_SET DZVP-GTH-PADE
      POTENTIAL GTH-PADE-q1
    &END KIND
    &KIND C
      BASIS_SET DZVP-GTH-PADE
      POTENTIAL GTH-PADE-q4
    &END KIND
  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
  PROJECT C2H4
  RUN_TYPE GEOMETRY_OPTIMIZATION
  PRINT_LEVEL MEDIUM
&END GLOBAL


On May 1, 4:08 am, Matthias Krack <matthia... at psi.ch> wrote:
> On Apr 30, 8:51 pm, Hanning Chen <chenh... at gmail.com> wrote:
>
> > Matthias,
>
> >   By only specifying "ROKS" with "OT", should I obtain the first excited
> > state singlet state (S1) or triplet state (T1) ?
>
> If you just specify ROKS with OT the corresponding high-spin state due
> to the selected multiplicity is calculated. This should be S0 for
> MULTIP=1 and T1 for MULTIP=3 in your case.
>
> Matthias
>
> > On Thu, Apr 30, 2009 at 2:38 AM, Matthias Krack <matthia... at psi.ch>wrote:
>
> > > Dear Hanning Chen,
>
> > > the implementation of low-spin ROKS with diagonalization (ROKS_SCHEME
> > > general) is still experimental and largely incomplete. For instance,
> > > the proper summation over the microstates contributing to a multiplet
> > > is missing. By contrast, the high-spin ROKS with diagonalization
> > > should work which is the default. This is why the result of your ROKS
> > > run did not differ from the RKS result. Alternatively, you may check
> > > the LOW_SPIN_ROKS available with OT.
>
> > > Matthias
>
> > > On Apr 30, 5:57 am, Hanning Chen <chenh... at gmail.com> wrote:
> > > > Dear CP2k community,
> > > >   I performed geometry optimization for C2H4 at first singlet excited
> > > state
> > > > (S1) using ROKS, and found that the optimized geometry is exactly same as
> > > > the ground state (S0). Can anyone help me to figure out the way to
> > > optimize
> > > > geometry at low-spin excited state? I also ran an geometry optimization
> > > at
> > > > first triplet excited state (T1) , and obtained a distinct geometry as
> > > > expected. I guess I might miss some key options in the input file shown
> > > > below.
>
> > > > Thanks.
>
> > > > Hanning Chen
> > > > Department of Chemistry
> > > > Northwestern University
> > > > Evanston, IL 60208
>
> > > > Input file:
>
> > > >   &FORCE_EVAL
> > > >   METHOD Quickstep
> > > >   &DFT
> > > >     ROKS
> > > >     MULTIPLICITY 1
> > > >     &QS
> > > >       EPS_DEFAULT 1.0E-8
> > > >     &END QS
> > > >     &SCF
> > > >       MAX_SCF 100
> > > >       SCF_GUESS ATOMIC
> > > >       &DIAGONALIZATION
> > > >        ALGORITHM STANDARD
> > > >       &END DIAGONALIZATION
> > > >     &END SCF
> > > >     &XC
> > > >       &XC_FUNCTIONAL PADE
> > > >       &END XC_FUNCTIONAL
> > > >     &END XC
> > > >   &END DFT
> > > >   &SUBSYS
> > > >     &CELL
> > > >       ABC 6.0 6.0 8.0
> > > >     &END CELL
> > > >     &COORD
> > > >     C         -0.2558206925       -0.0439868417        0.6850619693
> > > >     C         -0.2214915625       -0.0386665897       -0.6514432536
> > > >     H         -0.4100752923        0.8714166677        1.2581094627
> > > >     H         -0.1401850725       -0.9650616559        1.2579495323
> > > >     H         -0.0795226532       -0.9560364450       -1.2252531634
> > > >     H         -0.3528336094        0.8817708920       -1.2228724740
> > > >     &END COORD
> > > >         &KIND H
> > > >       BASIS_SET DZVP-GTH-PADE
> > > >       POTENTIAL GTH-PADE-q1
> > > >     &END KIND
> > > >     &KIND C
> > > >       BASIS_SET DZVP-GTH-PADE
> > > >       POTENTIAL GTH-PADE-q4
> > > >     &END KIND
> > > >   &END SUBSYS
> > > > &END FORCE_EVAL
> > > > &GLOBAL
> > > >   PROJECT C2H4
> > > >   RUN_TYPE GEOMETRY_OPTIMIZATION
> > > >   PRINT_LEVEL MEDIUM
> > > > &END GLOBAL
>
>