Subject: MP2 frequencies

From: [email-masked] (Anthony P Scott)
Date: Thu, 11 Aug 94 09:29:20 EST

I have mailed Errol directly with this reply but since at least one other
fellow computational chemist is not aware of our recent paper dealing withsubject I thought I might as well blow my own trumpet.

A paper dealing with the scaling factors that should be used when applied to
MP2-full/6-31g* harmonic vibrational frequencies appeared in Israel J. Chem.
1993, 33, 345. A scale factor of 0.9427 for frequencies and 0.9646 for
zero-point energies was derived for the MP2 method. This compares to values
of 0.8929 and 0.9135 respectively for HF/6-31G*.

Work has also been carried out here on deriving appropriate scale factors
for HF/6-311g**, HF/6-311G(df,p), MP2-fc/6-31G*, MP2-fc/6-311G**, BLYP/6-31G*,
BLYP/6-311G(df,p) methods.

Of current interest in the context of the original question is the scale
factors for MP2-fc/6-31g*. They have been determined to be 0.9434 cm-1 with
a RMS error slightly above that for the MP2-full results.

If there is enough interest in these results I might be able to post a
complete summary of them.

I hope this information is of some use.

Kind Regards,

Anthony P. Scott
Research Officer
Computational Chemistry Group
Research School of Chemistry
Australian National University
Canberra, ACT, Australia.