Hello everyone,
I need to calculate the optical rotation of a molecule by Gaussian 09 to confirm its absolute conformation. There are several papers suggesting the use of TDDFT/GIAO methodology to ensure reliable results (i.e., Org. Lett. 2002, 4, 4595-4598 ; J. Phys. Chem. A 2000, 104, 1039-1046 ).
What confuses me is that online manual of Gaussian describes the optical rotatoin calculation by only the keyword of poplar=optrot, and the desciption of GIAO is only in NMR section. I can't find anything relate GIAO with optrot keyword in the Gaussian manual. It looks like Gaussian doesn't require user to take care of GIAO when using poplar=optrot? Or is it possible that GIAO is used by default when launching poplar=optrot?
Anyway, I need to follow the suggested method to calculate optical rotation, which is TD-DFT/GIAO with big basis set containing diffuse function. The following is my temporary Route section for this calculation. Please let me know what I need to correct or what else I need to add.
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%nproc=12
%mem=20GB
# TD=(nstates=5) B3LYP/aug-cc-pVDZ poplar=optrot
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Thanks!
Sun