Ceilidh ... Re^6: excited state geometry opt and intersystem crossing

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Re^6: excited state geometry opt and intersystem crossing

On Thu Jun 10 '10 7:22pm, Vladimir A. Mironov wrote
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>Your system is nearly degenerate in the last point. So, the SCF procedure has become unstable. You may try to use state-averaged CASSCF method to locate minimum on the excited state. But it is really expensive procedure.

I do not agree that the procedure is expensive. The system has only ~700 orbitals, it is not much for a cluster and even for a good quad-core PC with enough disks. If the active space is not too large (say, 2-3 occupied and 2-3 virtual MOs), you may try. Unfortunately, I cannot see MOs in the attached output and cannot say, which MOs should be included in the active space.

Alternatively, you may increase MAXIT in the $CONTRL group to, say, 100 iterations. In this case, you'll face the instability problem a little bit later :)

Fri Jun 11 '10 2:41pm

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