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Re^4: SA2-CAS(2,2) calculation with cistep=ALDET and ISPIN=0

Alex Granovsky
gran@classic.chem.msu.su


Dear Bernhard,

sure GUGA works just fine. I think it was just a typo in the original
post by Evgeniy.

All the best,
Alex



On Sun Mar 5 '17 4:54pm, Bernhard Dick wrote
--------------------------------------------
>I am wondering why GUGA should not work. If you set MULT=1 in $CONTRL, only singlets will be calculated, so you do not need to worry where the energies of triplets are. just use WSTATE(1)=1,1 and NSTATE=2.
>best regards,
>Bernhard
>
>
>
>
>On Mon Feb 27 '17 9:38pm, GrEv wrote
>------------------------------------
>>Thanks for your response. Yes I set NSTATE to 2, because I want to do SA2-CASSCF(2,2) averaging over two singlet states S0 and S1. But this seems to be not possible with cistep=guga, because ISPIN doesn't work here, and without ISPIN one cannot select two singlet states, as the second state (after S0) is a triple.

>>Best regards,
>>Evgeniy

>>On Sat Feb 25 '17 10:29pm, Alex Granovsky wrote
>>-----------------------------------------------
>>>Hello,

>>>the ISPIN option works only with iterative Davidson eigensolver.

>>>With CASSCF(2,2) and alike, Hamiltonian matrix is tiny and is
>>>diagonalized directly using one of available diagonalization
>>>routines rather than iteratively, so that the ISPIN option is
>>>ignored.

>>>My guess is that you set NSTATE to 2 and got two states,
>>>namely lowest singlet and lowest triplet. This is why program
>>>complains (as it needs two singlet states). Use NSTATE=3 and
>>>you'll get two singlets and a triplet state.

>>>Kind regards,
>>>Alex Granovsky
>>>
>>>
>>>
>>>
>>>On Fri Feb 24 '17 2:18pm, GrEv wrote
>>>------------------------------------
>>>>Hello,

>>>>I have a question related to a SA2-CAS(2,2) calculation using cistep=ALDET and ISPIN=0.
>>>>I am interested in two singlet states, S0 and S1. Even with NSTGSS=4
>>>>the calculation crashes with the error:

>>>> ***** ERROR *****
>>>> THIS RUN FOUND    1 CI EIGENVECTORS WITH S= 0.00,
>>>> BUT YOU REQUESTED STATE AVERAGING OF    2 ROOTS.
>>>> PLEASE EXAMINE YOUR CHOICE OF -NSTATE- INPUT DATA.

>>>>So, I wonder if cistep=ALDET can be used in such a case, or only cistep=GUGA works here?

>>>>Best regards,
>>>>Evgeniy


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