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Re: Strange difference in configuration coefficients between the output of geom. optimization and the output of single-point calculation

Alex Granovsky
gran@classic.chem.msu.su

Hello,

This is what should be expected. CASCI expansion coefficients depend
on the rotations in the subspace of active MOs while CASSCF/CASCI
energy does not. Orbitals used during geometry optimization are not
the same as orbitals found in the punch file. The former more or less
arbitrary while the latter are either natural orbitals or
canonicalized MOs.

Kind regards,
Alex Granovsky

On Thu Mar 3 '16 4:04pm, GrEv wrote
-----------------------------------
>Hello,

>I encountered some strange inconsistency in the MCSCF WF coefficients printed out during a geometry optimization and at a single point calculation. I mean I performed a geom. optimization using SA2-CAS(2,2) and got a stationary point where the CAS WFs for two states look the following:

> STATE #    1  ENERGY =   -2511.331945658

>      CSF      COEF    OCCUPANCY (IGNORING CORE)
>      ---      ----    --------- --------- ----
>        1    0.529262  20
>        2   -0.713775  11
>        3    0.458701  02
>
> STATE #    2  ENERGY =   -2511.322269051
>
>      CSF      COEF    OCCUPANCY (IGNORING CORE)
>      ---      ----    --------- --------- -----
>        1    0.758665  20
>        2    0.156070  11
>        3   -0.632511  02

>When I performed a single point calculation at the optimized geometry (to get the orbitals) I however got the WFS that differ from the above WFs (fortunately the energies are the same):
>
>
> STATE #    1  ENERGY =   -2511.331945652

>      CSF      COEF    OCCUPANCY (IGNORING CORE)
>      ---      ----    --------- --------- -----
>        1    0.991938  20
>        2   -0.126662  11
>        3   -0.003975  02

> STATE #    2  ENERGY =   -2511.322269057

>      CSF      COEF    OCCUPANCY (IGNORING CORE)
>      ---      ----    --------- --------- -----
>        1   -0.126661  20
>        2   -0.991946  11
>        3    0.000508  02

>I wonder why it is so, what is the reason of the difference.
>Thanx!

>Best regards,
>Evgeniy

Sun Mar 6 '16 8:21pm