Re: On details of CASPT2 geometry optimization

Posted by Evgeniy on November 27, 2008 at 15:32:14:

In Reply to: Re: On details of CASPT2 geometry optimization posted by Valera on November 24, 2008 at 19:55:15:

:
: : 1) For a parallel CASPT2 geometry optimization run to be efficient is the number of CPUS should equal 6N+1 where N is the number of atoms?

: No. The optimization is done in internal coordinates, not in cartesians. This number is printed at the beginning of numerical gradient code.

:
: : 2) Is it possible to speed up the job further giving for instance more processors or/and memory?

: each individual job runs in serial. More memory clearly will help - since rasscf and caspt2 modules use disk a lot, and more memory will increase caching of I/O.

Valera,

Thanks for your responses.
Well, I have one more short question on caspt2 optimization,
namely whether one should specify in the CASPT2 input section
the option RLXRoot if one wants to optimize an excited state,
e.g. RLXRoot 2 for the first excited state. Or it is enough
just to specify Root 2 in ALASKA? Thanks!

Best,
Evgeniy

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Comments:
: : : : : 1) For a parallel CASPT2 geometry optimization run to be efficient is the number of CPUS should equal 6N+1 where N is the number of atoms? : : No. The optimization is done in internal coordinates, not in cartesians. This number is printed at the beginning of numerical gradient code. : : : : : 2) Is it possible to speed up the job further giving for instance more processors or/and memory? : : each individual job runs in serial. More memory clearly will help - since rasscf and caspt2 modules use disk a lot, and more memory will increase caching of I/O. : : Valera, : Thanks for your responses. : Well, I have one more short question on caspt2 optimization, : namely whether one should specify in the CASPT2 input section : the option RLXRoot if one wants to optimize an excited state, : e.g. RLXRoot 2 for the first excited state. Or it is enough : just to specify Root 2 in ALASKA? Thanks! : Best, : Evgeniy

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