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Re^2: frequencies in MCSCF

Alex Granovsky

Hi Jonas,

Yes, this structure is likely not a true minimum
and you are right lots of imaginary frequencies is probably
because of high symmetry. Look at the normal modes, you'll
note that T+R modes are not properly separated from vibrations.
To get reasonable Hessian, you need to re-optimize your
structure with tighter opttol and compute hessian with nvib=2

Alex Granovsky

On Thu Feb 10 '11 7:41pm, Jonas Baltrusaitis wrote
>There is something I can;t understand with these MCSCF frequencies. Now I did the same structure optimization+frequencies of first excited state and got bunch of negative frequencies. Is that because due to the high symmetry structure is not at a true minimum or there is somethin else going on?


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