From chemistry-request |-at-| server.ccl.net Fri May 24 07:05:56 2002 Received: from mail-b.bcc.ac.uk ([144.82.100.22]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id g4OB5u100518 for ; Fri, 24 May 2002 07:05:56 -0400 Received: from socrates-a.ucl.ac.uk by mail-b.bcc.ac.uk with SMTP (Mailer) with ESMTP; Fri, 24 May 2002 12:05:54 +0100 Received: (from uccatvm;at;localhost) by socrates-a.ucl.ac.uk (8.11.6+Sun/8.9.3) id g4OB5rY19857 for chemistry {*at*} ccl.net; Fri, 24 May 2002 12:05:53 +0100 (BST) From: uccatvm Message-Id: <200205241105.g4OB5rY19857 /at\socrates-a.ucl.ac.uk> Subject: Re: CCL:BSSE To: chemistry.,at,.ccl.net (CCL) Date: Fri, 24 May 2002 12:05:53 +0100 (BST) X-Mailer: ELM [version 2.5 PL3] MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Hi Olegas, > In the "standard" BSSE equation (for a dimer AB): > > BSSE(AB) =3D E(AB)^AB - E(A)^A - E(B)^B + [E(A')^A - E(A')^AB + E(B)^B - = > E(B)^AB] > > I've got most of the parameters, but how in G98W do I calculate E(A)^AB = > and E(B)^AB, i.e. the energy of the monomer units in terms of the dimer = > basis set. With Gaussian, the keyword Massage has to be used for counterpoise corrections (assuming it's the same for G98 and G98W). Have a look at the Gaussian manual: http://www.gaussian.com/00000452.htm. There is an example there as well. However, don't believe the sentence about counterpoise being only a crude estimate, have a look at the following papers to learn more about BSSE and Counterpoise: - F.B. van Duijneveldt, J.G.C.M. van Duijneveldt-van de Rijdt, and J.H. van Lenthe, Chem. Rev. 94, 1873, 1994 (on counterpoise theory) - S. Simon, M. Duran, J.J. Dannenberg, J. Chem. Phys. 105, 1996 (on geometry optimizations on BSSE-corrected potential energy surfaces). - F.B. van Duijneveldt, "Basis Superposition Error" in "Molecular Interactions" S. Scheiner (ed.), Wiley (1997) - T. van Mourik, A.K. Wilson, K.A. Peterson, D.E. Woon, T.H. Dunning, Jr., Adv. Quant. Chem. 31, 105, 1999 (showing BSSE effects on interaction energies, distances, and frequencies). HTH, Tanja -- ===================================================================== Tanja van Mourik Royal Society University Research Fellow Chemistry Department University College London phone: +44 (0)20-7679-4663 20 Gordon Street e-mail: work: T.vanMourik- at -ucl.ac.uk London WC1H 0AJ, UK home: tanja "-at-" netcomuk.co.uk http://www.chem.ucl.ac.uk/people/vanmourik/index.html =====================================================================