Subject: DFT and FREQ?

From: [email-masked] (Magda Wajrak)
Date: Fri, 21 Jan 94 15:32:46 WST

Hello,

I just wanted to ask, if anyone could tell me how good is the DFT method in
calculating vibrational frequencies. I am particularly interested in its
performance for open-shell molecules. 
I have been recently told that open shell MP2 frequencies are not very good,
and so I have decided to try DFT.  Has anyone done any such calculations?

Any comments will be appreciated.

Thank you very much.

Magda Wajrak

([email-masked])

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From: Gustavo Mercier <[email-masked]>
Date: Fri, 21 Jan 1994 14:08:43 -0500 (EST)

> performance for open-shell molecules. 

They appear to be pretty good. This is no surprise since DFT seems to
do a pretty good job with energetics and geometries, although you will
need to include gradient corrections to the exchange-correlation functional
for accurate work. Some references:

Density Functional Methods in Chemistry
eds. J.K. Labanowski and J.W.Andzelm
pub. Springer-Verlag
1991 ISBN: 0-387-97512-8

Check out the article in page 77 by D. R. Salahub et. al., "Gaussian -
based Density Functional Methodology, Software, and Applications"

Also, the following article addresses relativistic effects within the
Hartree - Fock - Slater formalism as implemented by Baerends (essentially
Xa method with LCAO-MO), but includes frequencies computed for heavy TM:

Relativistic effects on bonding
T. Ziegler et. al.
J. Chem. Phys. 74(2), 15 Jan. 1981
p. 1271

good luck
gus mercier
[email-masked]