Posted by Saumik Sen on January 29, 2013 at 12:42:32:
I was running a CASSCF optimization for [2Fe-2S] system, but for the singlet multiplicity the core was getting bent. Even CASPT2 calculation failed to give a good structure.
Then I tried to optimize it by freezing only the core to its DFT geometry and now it finally become optimized giving a good structure.
My question is whether it will be acceptable to have frequency calculation on this partial freeze structure? Whether it is methodically wrong to do frequency calculation on a structure which is not fully optimized with the same method and basis?
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