Subject: Spin Density vs SOMO surfaces

From: Pascal Gosselin <gosselin.-at-.univ-lemans.fr>
Date: Mon, 15 Mar 2004 15:45:00 +0100

Dear all,

I wanted to visualize the localization of the unpaired electron
in radical-cations whose structures were optimized at the UB3LYP/6-31G*
level in Gaussian98.
For that purpose, I asked Gaussview to compute both Spin Density and 
SOMO surfaces.
In most cases, both pictures were very similar. However, in some cases,
I was surprised to observe two very different pictures, i.e.
the surfaces were located over completely different regions of the 
radical-cation.

In some cases, alphaSomo, alphaSomo-1 and betaSomo were found very 
close in energy.
I tried to obtain a "mean view" of the system by adding the alphaSomo 
and  alphaSomo-1
then subtracting betaSomo (with the cubman utility within g98 package).
The resulting picture remained different of the Spin Density surface.

Has somebody an explanation?

All the Best

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Dr Pascal Gosselin
Laboratoire de Synthhse Organique/UMR-CNRS-6011
Faculti des Sciences & Techniques
Universiti du Maine
Avenue Olivier Messiaen
F-72085 Le Mans Cedex 9 France
Tel: + 33 (0)2 43 83 33 71
Fax: + 33 (0)2 43 83 39 02
Email: Pascal.Gosselin.-at-.univ-lemans.fr
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