Subject: MCSCF freq. + scaling factors

From: "Dr. Adel El-Azhary" <[email-masked]>
Date: Mon, 5 Aug 96 15:27:17 METDST

Dear Gwaltney:
 
My impersion is that the CISD method performs worth than MP2 method at
an extra computational cost. This led to a focus on the MP2 method rather 
than the CISD method. You can look at different papers by Schaefer which
compares between the CISD and MP2 frequencies. In one of these, although not 
the best example, he reported the HF and CISD frequencies for thiirane and
thiirene (J. Chem. Phys., 84, 4211, 1986). Concerning the MCSCF frequencies, 
we reported eariler, (J. Phys. Chem., 99, 12751, 1995) a comparison between
the HF, MP2, MCSCF and B3LYP optimized geometries, frequencies, intensities
and scale factors. The conclusion which was drawn is that the MCSCF and HF 
methods performed similarly due to the samll active space used in the MCSCF
calculations.

Adel El-Azhary
Institute for Theortical chemistry
Stuttgart University
Stuttgart, Germany