[molpro-user] CASPT2 convergence problem

[Werner Győrffy]

Dear Yang,

You can try to increase the the number of configurations in the primary 
configuration space by using the PSPACE card. Increase the threshold 
value to, for example, 1 (PSPACE,1). In the primary configuration space, 
the Hamiltonian is constructed and diagonalized explicitly which may 
stabilize your CASPT2 calculations. For further details, see PSPACE in 
the manual.

Regards,

Werner Gyorffy.

On 11/05/2013 09:02 PM, Yang Yang wrote:
> Hi, Dear Molpro Community,
>
> I'm trying to solve the lowest 3 excited states with a particular
> symmetry and spin in a CASPT2 calculation. The previous state-averaged
> CASSCF calculation *always* converges successfully. However, only the
> first excited state in the CASPT2 calculation can converge. If I include
> the second or/and third state(s) in a multi-state CASPT2 or solve the
> second/third state individually, then there is no convergence.
>
> I have tried to use different CASSCF reference states as the initial
> guess, modify the level shift or increase the iteration number. None
> worked so far. Any other things i may try to help the convergence?
>
> Thanks a lot!
>
> Sincerely
>
> yang
>
>
>
>
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