From owner-chemistry@ccl.net Mon Dec 17 08:55:01 2007
From: "Tom de Greef t.f.a.d.greef|-|tue.nl" <owner-chemistry\a/server.ccl.net>
To: CCL
Subject: CCL:G: PCM and TD-DFT
Message-Id: <-35871-071217042823-19502-mhmGvCWKb97lUG8JeArnAA\a/server.ccl.net>
X-Original-From: "Tom de Greef" <t.f.a.d.greef],[tue.nl>
Date: Mon, 17 Dec 2007 04:28:20 -0500


Sent to CCL by: "Tom de Greef" [t.f.a.d.greef|*|tue.nl]
Dear all,
I have a question about the use of TD-DFT calculations including PCM solvent effects using Gaussian 03. I have read in several papers that the best method to use the PCM solvent model in combination with TD-DFT is the non-equilibrium approach (when one is interested in the fast absorption processes). The solvent reaction field in the non-equilibrium regime depends in the PCM formalism on the dielectric constant at optical frequency (for CHCl3 this is 1.2). The default TD-DFT calculations in Gaussian03 assumes a non-equilibrium approach (NonEquilSolv is default). However, when I start a TD-DFT calculation in Gaussian03 for CHCl3 it automatically takes the value of the dielectric constant (for CHCl3 this is 4.9) for the calculation. Does this mean that I need to define the dielectric constant in an explicit way (by addition of the keyword: EPS=1.2)???

With best regards,

Tom