ROKS input

[Matthias Krack]

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
>
>