[molpro-user] caspt3 excited states

[Toru Shiozaki]

Dear Benjamin,
In Molpro, the internal part of the wave function is obtained by the Davidson-like CI,
and if the initial guess vectors have no overlap with the target vector, it will fail
to converge to the desirable root (the use of the lower symmetry might be
related in your case).

I think that the easiest solution to the problem at hand is to use
{rs3;state,1,5;options,nstati=6}
which increases the number of roots to be obtained in the internal CI process.

It might also help if you play with the "pspace" keyword (see the reference sec.20.3.9).
The Hamiltonian matrix in pspace configurations is diagonalized
before the first iteration to prepare the initial guess for the internal vectors.
{rs3;state,1,5;pspace,1.0}  ! Not sure it works... if you don't like the first solution.

Best wishes,
Toru

On Jan 19, 2011, at 11:25 PM, Mintz, Benjamin J. wrote:

> To users,
> 
> I am trying to compute an excited state without symmetry. The excited state that I would like to compute is the 5th excited state.  The multi step gives me the following for the energies
> 
> !MCSCF STATE 1.1 Energy             -192.119014929625
> !MCSCF STATE 2.1 Energy             -192.093454846540
> !MCSCF STATE 3.1 Energy             -192.058662803146
> !MCSCF STATE 4.1 Energy             -192.055868714916 
> !MCSCF STATE 5.1 Energy             -192.028038675647
> 
> 
> The problem is when I try to do the rs3 part.  If I do {rs3;state,1,5}, I get the following for the reference energies
> 
> State     Reference Energy
>   5        -192.00552318
>   3        -192.05866280
>   4        -192.05586871
>   1        -192.11901493
>   2        -192.09345485
> 
> Specifically, the reference energy for the 5th excited state does not match the MCSCF STATE 5.1, and the computation fails to converge.  If I do {rs3;state,1,6}, I get the following
> 
> State     Reference Energy
>   5        -192.02803868
>   6        -192.00552318
>   3        -192.05866280
>   4        -192.05586871
>   1        -192.11901493
>   2        -192.09345485
> 
> 
> The reference energy for the 5th excited state now matches the MCSCF STATE 5.1 energy, and the 6th excited state matches the 5th excited state from the {rs3;state,1,6}.  However, I do not want to compute the 6th excited state.   I want the 5th excited state.  Why is the 6th excited state being computed for the 5th excited state when I do {rs3;state,1,5}?  Is there a work around for this problem, or is there a problem in my computation?
> 
> Benjamin J. Mintz
> Research Associate, Postdoctoral
> Oak Ridge Leadership Computing Facility (OLCF)
> Oak Ridge National Laboratory
> Phone: (865) 574-6639
> Email: mintzbj at ornl.gov
> Gmail: bm0037 at gmail.com
> 
> 
> 
> 
> 
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