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Re: Question on CSFs: the same CSFs in the WF expansion

Alex Granovsky
gran@classic.chem.msu.su


Hello,

below, "OCCUPANCY" means orbital configuration.

There exist CSFs with identical orbital configuration but with
different spin coupling. This is what you see in your output.

Kind regards,
Alex Granovsky


On Fri May 6 '16 8:59pm, GrEv wrote
-----------------------------------
>Hello,

>I wonder how to interpret the same CSFs (configurations) in the WF expansion in a CASSCF calculation. In particular, I have the following expansion for a singlet (excited) state:

>     CSF      COEF    OCCUPANCY (IGNORING CORE)
>...
>    67033   -0.060115  222211101000
>    74594   -0.114228  222211101000
>...
>    88706    0.066301  222121110000
>   118407    0.162652  222121110000
>...

>As can be seen, CFSs 67033 and 74594 as well as 88706 and 118407 look the same, though contribute with different coefficients. I guess these are let's say \alpha \alpha \beta \beta and \alpha \beta \beta \alpha configurations, i.e. double-excitation of the parallel and anti-parallel by spin electrons (like in MP2). Is it possible to say which of the same configurations corresponds to excitation of parallel and anti-parallel electrons?
>
>
>Best regards,
>Evgeniy


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