From chemistry-request ":at:" ccl.net Fri Jul 8 14:30:34 2005 Received: from mailTM.sued-chemie.de (mailtm.sued-chemie.de [195.145.99.198]) by server.ccl.net (8.13.1/8.13.1) with ESMTP id j68IUWJQ012711 for ; Fri, 8 Jul 2005 14:30:33 -0400 Received: by mailTM.sued-chemie.de (Postfix, from userid 65534) id E7DA21A7714; Fri, 8 Jul 2005 20:33:32 +0200 (CEST) Received: from mailtm2.sued-chemie.com (unknown [172.16.1.15]) by mailTM.sued-chemie.de (Postfix) with SMTP id 57F6D1A75B1 for ; Fri, 8 Jul 2005 20:33:31 +0200 (CEST) Received: from srvkyem1.americas.sc-world.com ([10.16.100.68]) by srv49003.scag.sc-world.com with Microsoft SMTPSVC(5.0.2195.6713); Fri, 8 Jul 2005 20:29:45 +0200 X-MimeOLE: Produced By Microsoft Exchange V6.0.6556.0 content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Subject: RE: W:Symmetry breaking during CASSCF Date: Fri, 8 Jul 2005 14:29:43 -0400 Message-ID: <9DD56492790889439F731F5BD6DACA0009B63F8C|at|srvkyem1.americas.sc-world.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: W:Symmetry breaking during CASSCF Thread-Index: AcWD2UP9NJ/abOpnQBy5Lv5RX7WRggAESgzQ From: "Shobe, David" To: X-OriginalArrivalTime: 08 Jul 2005 18:29:45.0384 (UTC) FILETIME=[03C6CA80:01C583EB] X-Spam-Checker-Version: SpamAssassin 3.0.4 (2005-06-05) on server.ccl.net X-Spam-Level: X-Spam-Status: No, score=0.0 required=5.0 tests=none autolearn=failed version=3.0.4 Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by server.ccl.net id j68IUYJQ012715 Jahn-Teller effect, perhaps? Does the D2h geometry have degenerate orbitals which become non-degenerate once the symmetry is broken? --David Shobe, Ph.D., M.L.S. S|d-Chemie, Inc. phone (502) 634-7409 fax (502) 634-7724 Don't bother flaming me: I'm behind a firewall. -----Original Message----- From: Computational Chemistry List [mailto:chemistry-request|at|ccl.net] On Behalf Of Gustavo, L.C., Moura Sent: Friday, July 08, 2005 7:35 AM To: chemistry|at|ccl.net Subject: CCL: W:Symmetry breaking during CASSCF Dear CCL Readers, I have a planar conjugated organic molecule that, on paper, has D2h symmetry. I am working with the hypothesis that the molecule is a biradical singlet. I want to perform a CASSCF(2,2) on this molecule to estimate the biradical character of this molecule. When I calculate the molecule with the constraint that the molecule has D2h symmetry, the calculation has severe convergence problems. If I remove this constraint, the molecule distorts to a C2v symmetry and I obtain a biradical character ~20%. I checked the orbitals being used for the CASSCF calculation and they look right (one nonbonding and another slightly antibonding). Is the situation described above correct? Can an organic molecule have such a symmetry breaking as a result of a CASSCF calculation? Is the molecule really a C2v system? Any suggestions are welcome. Thank you very much in advance for your help. Sincerely yours, Gustavo L.C. Moura gustavo|at|mercury.chem.pitt.edu -= This is automatically added to each message by the mailing script =- To send e-mail to subscribers of CCL put the string CCL: on your Subject: line and send your message to: CHEMISTRY|at|ccl.net Send your subscription/unsubscription requests to: CHEMISTRY-REQUEST|at|ccl.net HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs If your is mail bouncing from ccl.net domain due to spam filters, please use the Web based form from CCL Home Page -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+