From chemistry-request %-% at %-% server.ccl.net Mon Jan 31 09:25:14 2000 Received: from mozart.si.ualg.pt (mozart.si.ualg.pt [193.136.224.2]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id JAA10817 for ; Mon, 31 Jan 2000 09:25:13 -0500 Received: from beethoven.si.ualg.pt (beethoven.si.ualg.pt [193.136.224.64]) by mozart.si.ualg.pt (8.9.1/8.9.1) with ESMTP id NAA32314; Mon, 31 Jan 2000 13:02:05 GMT Received: by beethoven.si.ualg.pt with Internet Mail Service (5.5.2232.9) id ; Mon, 31 Jan 2000 13:03:08 -0000 Message-ID: From: Joao Brandao To: jochen*- at -*uni-duesseldorf.de Cc: chemistry(+ at +)ccl.net Subject: RE: bsse and second derivatives in G98 Date: Mon, 31 Jan 2000 13:03:05 -0000 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2232.9) Content-Type: text/plain I think it is a mathematical problem, not a physical one. Being the BSSE a correction done subtracting different energies and the force field a second derivative of the energy, it should be OK to subtract the different force fields to account for a force-field BSSE corrected. Instead of compute a BSSE corrected energy for each configuration and numerically compute the second derivatives of the potential energy surfaces, we can compute numerically the second derivatives for each term and BSSE correct those second derivatives. If the steps in the numeric procedure are the same the results should be the same. If we calculate analytically the derivatives, better. Joao Brandao --------------------------------------------------------------------- Quimica - UCEH Universidade do Algarve -Campus de Gambelas P-8000 FARO Portugal e-mail: jbrandao ^at^ ualg.pt Tel. 0351-89-800900 ext. 7453 Fax. 0351-89-819403 --------------------------------------------------------------------- After I sent this message, I notice the one from Artem Masunov that, I think, explains correctly the problem. Joao Brandao