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Re^3: SA2-CAS(2,2) calculation with cistep=ALDET and ISPIN=0

Bernhard Dick
bernhard.dick@chemie.uni-regensburg.de


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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