From chemistry-request ^at^ ccl.net Fri May 20 17:22:22 2005 Received: from mta1.appstate.edu (mailhub.appstate.edu [152.10.1.150]) by server.ccl.net (8.13.1/8.13.1) with ESMTP id j4KLMH9C018015 for ; Fri, 20 May 2005 17:22:18 -0400 Received: from ws2.appstate.edu (ws2.appstate.edu [152.10.1.41]) by mta1.appstate.edu (8.12.11/8.12.11) with ESMTP id j4KKMHiU000934 for ; Fri, 20 May 2005 16:22:18 -0400 Received: from pople.appstate.edu (willsd-1.chem.appstate.edu [152.10.116.55]) by appstate.edu (PMDF V6.2-1x5 #30887) with ESMTP id <01LOHK2AVI7SBCB15V ## appstate.edu> for CHEMISTRY ## ccl.net; Fri, 20 May 2005 16:20:11 -0400 (EDT) Date: Fri, 20 May 2005 16:22:16 -0400 From: Steve Williams Subject: CCL: TD-DFT singlets vs triplets intensity To: CHEMISTRY ## ccl.net Message-id: <6.2.1.2.0.20050520161150.01eaa6b0 ## imap.appstate.edu> MIME-version: 1.0 X-Mailer: QUALCOMM Windows Eudora Version 6.2.1.2 Content-type: text/plain; format=flowed; charset=us-ascii X-MailScanner-Information: Please contact the Helpdesk - at - 6266 for more information X-MailScanner-ASU-mta1: Found to be clean X-MailScanner-SpamCheck: X-MailScanner-From: willsd ## appstate.edu X-Spam-Status: No, score=0.0 required=5.0 tests=none autolearn=failed version=3.0.3 X-Spam-Checker-Version: SpamAssassin 3.0.3 (2005-04-27) on server.ccl.net I have carried out some TD-DFT calculations in G03 on two rather large (about 150 atoms) molecules that each have a single Re atom in the center of the molecule. For each I have 50 singlet and 50 triplet states; the molecular ground state is a singlet (nice sharp NMR spectra). Of course G03 gives oscillator strengths of zero for each triplet excitation, since the calculation does not use spin-orbit effects. With a heavy atom like Re, the spin orbit coupling will be large, and this will likely cause the triplet excitations to contribute to the observed spectrum. I have thought about looking at each of the orbitals involved in each excitation and identifying those that have some contribution from the Re atom. I think the excitations involving these should make some contribution to the absorbance spectrum. Does anyone have any suggestions about how to estimate (even crudely) the oscillator strengths of these excitations? Thanks, Steve Steve Williams A. R. Smith Department of Chemistry Appalachian State University Boone, NC 28608 USA 828-262-2965