Subject: Re: CCL:Gaussian Raman Intensities in Solution

From: "Dr. Andreas Klamt" <[email-masked]>
Date: Wed, 07 Feb 2001 07:22:53 +0100

Although I am not familiar with the details of the COSMO implementation in Gaussian, 
being the author of the original COSMO I like to shortly comment on the general 
question of Raman intensities in solution:

Note, that high vibrational frequencies in solution are definitely not in equilibrium 
with the reorientational part of the solvent polarization. Therefore calculation of second 
derivatives of the total energy are not adequate for vibrational frequencies. The 
best way to calculate the Raman frequencies in solution would be 
- to first do geometry optimization in the solvent
- then freeze the polarization charges
- do second derivatives while treating the (molecule + frozen equilibrium polarization charges)
as embedded in a medium of electronic polarizability (eps=2).

I am not sure, whether such treatment is possible in Gaussian, 
but it efinitely would be the physically most correct way to do it.

Andreas Klamt

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Dr. Andreas Klamt
COSMOlogic GmbH&CoKG
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51381 Leverkusen, Germany

Tel.: 49-2171-73168-1  Fax: ...-9
e-mail: [email-masked]
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