Subject: BSSE

From: [email-masked] (Marek Sierka)
Date: Tue, 14 Nov 1995 18:57:01 +0100

Dear Moshe,

        Good basis set has to be properly balanced, otherwise it introduces
so called Basis Set Superposition Error. In case of the unbalanced basis set,
it leads to the artificial charge transfer, and also gives nonphysical,        
stabilizing contributions to the enery of molecule. This stabilizing will
then occure irrespective of whether there is any genuine binding interaction
in the molecule or not. It will give a spurious increase in the binding 
energy.The choice of proper basis set is kind of art, so you have to be
very careful about it. Try this:                                               
  
http://www.emsl.pnl.gov:2080/forms/basisform.html
This www server contains several basis sets, so maybe you can find
something useful.

Marek Sierka
Max-Planck Society
Quantum Chemistry Group at the Humboldt Univ.
Joegerstrasse 10/11
D-10117 Berlin, Germany
e-mail: [email-masked]