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Re^2: Why the MCSCF calculation drops the n orbital from active space?

Panwang Zhou
pwzhou@gmail.com


Dear Prof. Alex,

Thanks for your comment.

I have successfully captured the n-pi* state after I adjust the geometry of the molecule and then perform a SA4-CASSCF(12,11) calculation.

On Sun Mar 22 '15 1:44pm, Alex Granovsky wrote
----------------------------------------------
>Dear Panwang Zhou,

>In fact this is very logical result. To keep n orbital in active space
>you need to allow this orbital to correlate with another orbital in
>the active space. There are two ways how you can arrange this: you can
>either perform SA-MCSCF to capture n-pi* excited state or to add the
>corresponding n* orbital to the active space.
>
>
>Kind regards,
>Alex Granovsky
>
>
>
>On Wed Mar 18 '15 10:04am, Panwang Zhou wrote
>---------------------------------------------
>>Dear all,

>>Recently I carried out MCSCF calculations on a molecule where the n->pi* transition plays an important role. I selected the several lowest pi and pi* orbitals and the n orbital on the O atom of C=O group from the HF MOs. However, both the obtained MCSCF natural orbitals and MOs did not contain the n orbital. I have tested the CAS(10,9), CAS(12,11),CAS(12,10) calculations, all the optimized MCSCF orbitals drop the n orbital to the highest core orbital. This is unreasonable and I don't know why this occurs.

>>As an example, I supplied the input and output files of CAS(12,11) calculation results in the attachment.

>>Best Regards!

>>


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