Subject: Re: CCL:MOLECULAR MECHANICS CALC OF IR SPECTRA

From: "Rafael R. Pappalardo" <[email-masked]>
Date: Wed, 23 May 2001 06:49:09 +0200 (CEST)

On Tue, 22 May 2001, elewars wrote:

> 2001 May 22
>
> Hello,
>
>     Molecular mechanics programs can now calculate the positions
> (cm**-1) of normal-mode vibrations. However, MM by itself cannot
> calculate the _intensities_ of these vibrations, since this depends on
> the change in dipole moment, which in turn depends on electron
> distribution, a concept outside MM theory.
>
>     It seems, however, that in principle MM could calculate intensities
> using assigned bond moments or atom charges, which would provide a rapid
> way of calculating IR spectra. Has this been implemented in any program?
>
> Thanks
>
> E. Lewars
> ========
>
>
You should check the book by K. Machida "Principles of molecular
mechanics". I believe that the RISE program by the same author is able
to calculate IR intensities.

Rehards

-- 
Dr. Rafael R. Pappalardo
Dept. Quimica Fisica, Fac. de Quimica, Univ. de Sevilla. 41012-Sevilla (Spain)
e-mail: [email-masked]