Subject: CCL: dissociation problem in PCM model ?

From: Elmar Gerwalin <elg !v! chemie.uni-kl.de>
Date: Thu, 7 Jul 2005 22:29:35 +0200

Hi,

I'm trying to describe dissociation processes in some small organic molecules.
Therefore, I'm using B3LYP+SCRF(C-PCM, solvent=methanol) single point jobs to get the 
solvation energy at each step. Finally, a potential energy curve E(R) is my goal.
R is the bond distance I'm interested in; e.g. a C-O, C-Cl bond or , for testing purposes
Na-Cl.

But, unfortunately, wrong asymptotic behaviour (like a "size inconsistency problem") is 
observed in all cases: the "supermolecule's" solvation energy at large distances (10 or 20 A) 
is differing about more than 20 kcal/mole from the sum of the solvation energies of the two ions.

My question is: is the problem known (references ?)? How can be it be accounted for ?
Do I have to use specific energy terms given in gaussian's output and/or male a correction to them ?

Any help is appreciated.

Bye,

Yours,
 Elmar

-- 
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Elmar Gerwalin ,   University of Kaiserslautern,Germany
                   Dept. of Theoretical Chemistry
                   elg !v! chemie.uni-kl.de    
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