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Re^3: Freezing multiplicity of parts or smth like this...


The feature you're looking for is called "broken symmetry" SCF. It is not implemented in FireFly (I know it's implemented in ORCA). Actually, CASSCF is more theoretically sound method. By CASSCF implemented in FireFly, you can treat up to 1000 basis functions with reasonable active spaces (up to (16,16)).

On Wed Nov 30 '11 3:30pm, Alex Nest wrote
>On Wed Nov 30 '11 2:27pm, Alex Granovsky wrote
>>Hi Alex,

>>try to use CASSCF with carefully chosen active space.
>>To distinguish two state, look at spin densities (when available),
>>and on bond order/free valence indices.

>Thank you, Alex. But I suppose this is the way to DISTINGUISH but not to SEPARATE this two states. Is there any techniques to "freeze" A[S1]-B[T] state before transition occurs? I suppose in some conformations final vectors should be consist of both A[S1]-B[T] and A[T]-B[S1] CSFs and if, for instance, A[T]-B[S1] is energetically favorable, a contribution of correspondent CSFs will dominate.

>Sincerely yours,

>>Alex Granovsky
>>On Wed Nov 23 '11 2:41pm, Alex Nest wrote
>>>Dear colleagues, please help me to solve the next problem:
>>>In the intermolecular complex AB energy migration takes place:
>>>(1) A[S1] + B[T] --> (2) A[T] + B[S1]. How could I distinguish and separate these states (1 and 2) one from another?


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