From chemistry-request@ccl.net Tue Dec 14 09:59:10 2004 Received: from up.univ-mrs.fr (mailup.univ-mrs.fr [147.94.113.16]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id iBEEx9hd004553 for ; Tue, 14 Dec 2004 09:59:09 -0500 Received: from localhost (localhost [127.0.0.1]) by up.univ-mrs.fr (Postfix) with ESMTP id CCC941E8E4D; Tue, 14 Dec 2004 16:14:45 +0100 (CET) Received: from up.univ-mrs.fr ([127.0.0.1]) by localhost (mailup.univ-mrs.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 232948-06; Tue, 14 Dec 2004 16:14:45 +0100 (CET) Received: from [147.94.185.160] (unknown [147.94.185.160]) by up.univ-mrs.fr (Postfix) with ESMTP id 05B4A1CB498; Tue, 14 Dec 2004 16:14:45 +0100 (CET) Message-ID: <41BF0367.5020604(at)up.univ-mrs.fr> Date: Tue, 14 Dec 2004 16:14:47 +0100 From: =?ISO-8859-1?Q?Nicolas_Ferr=E9?= Organization: LCTMM User-Agent: Mozilla/5.0 (X11; U; Linux i686; fr-FR; rv:1.7.2) Gecko/20040804 X-Accept-Language: fr-fr, en-us, en MIME-Version: 1.0 To: help(at)gaussian.com Cc: CCL posting Subject: Gaussian03: MP2 before CI or CC X-Enigmail-Version: 0.85.0.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at up.univ-mrs.fr X-Spam-Status: No, hits=4.0 required=7.5 tests=NO_RDNS,NO_RDNS2,RM_ft_Iso8859 autolearn=no version=2.61 X-Spam-Checker-Version: SpamAssassin 2.61 (1.212.2.1-2003-12-09-exp) on servernd.ccl.net Dear all, When you run a CI or CC job with g03, it starts by resolving the HF equations. In the next step, the integrals are expressed over MOs and then the first-order MP wavefunction (and the second-order MP energy) are computed, all of this done in the link 804. Finally, g03 uses these informations for the CI or CC job in the link 913. I would like to find references about this procedure. I guess it is related to the Davidson scheme for diagonalizing the CI matrix. But why always using the MP wavefunction instead of the HF one ? Is there an option in g03 for using the HF wavefunction ? What is more surprising is that the CI or CC energy depends on the MO eigenvalues ! I just slightly modified the code in link 801 for changing one eigenvalue (rwf 547) and the final CI or CC energy varies with this eigenvalue ! I checked the same behavior on different machines. Can someone explain what is happening ? I guess I am missing something but I cannot find what. -- Dr. Nicolas Ferre' Laboratoire de Chimie Theorique et de Modelisation Moleculaire UMR 6517 - CNRS Universite' de Provence Case 521 - Faculte' de Saint-Jerome Av. Esc. Normandie Niemen 13397 MARSEILLE Cedex 20 (FRANCE) Tel : (+33)4.91.28.27.33 Fax : (+33)4.91.28.87.58 Please avoid sending me Word or PowerPoint attachments. See http://www.gnu.org/philosophy/no-word-attachments.html