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Re^3: Averaging states of different symmetries in the same run


Dear all,

I would like to make a small addition to Pavel's suggestions. With Firefly 8.0.0, it is no longer necessary to specify $CONTRL NOSYM=1 $END if one would like to perform a XMCQDPT2 calculation with states beloning to different irreps. Instead, one can now specify $XMCQDPT ISTSYM=-1 $END to disable symmetry during the XMCQDPT2 step. This naturally also applies to MCQDPT2 calculations.

Kind regards,

On Tue Mar 5 '13 1:01am, Solntsev Pasha wrote
>Dear Antonio.

>I had the same problem with some macrocycles. But in my case the symmetry was much higher. I "bugged" Alex a lot about this issue to get answer on the same question as you have. As far as i know, with FF8 you can't do SA-MCSCF over states with different symmetries. You can use different symmetries (using ALDET code), but not symmetries. The strategy i used is follow:
>Do geometry optimization using full point group symmetry. Then ,if states of interest have different symmetry (such as ground state and excited states) set group=c1 and use wstate(1) to select desire states (for example, ground state and only symmetry allowed states). If you have transition from single degenerated state to a double degenerated one, don't forget to include both configurations (transition double degenerated) into SA.
>After SA-MCSCF is done you the results were checked and you love them, you can setup XMCQDPT with $CONTRL NOSYM=1 $END. This option switch off the symmetry completely during XMCQDPT job. Again, you may use KSTATE(1), WSTATE(1), AVECOE(1) to select the states of interest.

>My observation about SA-MCSCF/XMCQDPT code. It is really very fast. For your molecule it is not a problem at all even without symmetry. Do some search withing this forum and you will find more professional comments from experts.

>Good luck.

>On Mon Mar 4 '13 11:26pm, sanya wrote
>>You may try PURES=.f., it permits state-averaging over states with different multiplicity. It may also work for the states of different symmetry, but I am not sure, you'll better try and see.

>>On Sat Mar 2 '13 3:23pm, Antonio Carlos Borin wrote
>>>Dear Prof. Alex,

>>>In reply to your message, Im posting the input file and I will try to better explain what I want to do.

>>>Please, note that it is the input file you sent me in reply to a previous question about excited states I posted on Mon Feb 18 '13 4:01pm.

>>>Dr. Solntsev Pasha was of great help, but maybe you can find other solution.

>>>I want to compute the excited states of adenine, employing Cs symmetry; therefore, I need to compute A' and A'' states.

>>>In MOLPRO and ORCA, for instance, we can do state-average casscf (sa-casscf) averaging over states belonging to different irreducible representations. So, the A' and A'' states can be computed in the same run. In MOLCAS this is not possible and we have to compute the A' states in a step and the A'' states in other step.

>>>My question is: is it possible to do the sa-casscf and XMCQDPT calculations averaging over the A' and A'' states in the same job? Or we need to do it as with MOLCAS.

>>>As Dr. Solntsev Pasha said, it is possible to do it without symmetry, the "default" solution. But I would like to know if it is possible to do it employing symmetry (Cs in this case).

>>>Which keywords do I need to add to the attached input file to do it?

>>>Thank you for your attention
>>>Best regards,

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