From owner-chemistry@ccl.net Thu Sep 1 15:52:01 2011 From: "Jason D Acchioli jdacchio#,#gmail.com" To: CCL Subject: CCL:G: TD DFT percent contributions Message-Id: <-45372-110901155052-14798-nm1LCRUFgCAqLGEbiQzTvA : server.ccl.net> X-Original-From: "Jason D'Acchioli" Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=us-ascii Date: Thu, 1 Sep 2011 14:50:36 -0500 Mime-Version: 1.0 (Apple Message framework v1244.3) Sent to CCL by: "Jason D'Acchioli" [jdacchio/a\gmail.com] Hi all, I have a technical question regarding the interpretation of TD-DFT results from any program, but using Gaussian as the most readily-available example. A typical Gaussian (G09) output lists several excitations calculated. Excited State 8: Singlet-A 3.2952 eV 376.26 nm f=0.1749 =0.000 95 ->102 -0.11772 96 ->100 0.64507 98 ->101 -0.23293 I've seen several posts on calculating the percent contributions of orbitals to the specified transitions, as (coefficient)^2 x 2 x 100 = percentage. So, for 96 -> 100 above, the contribution would be 82%. What about the negative signs? From similar posts on here, I've seen that the sign is ignored. However, at the PC Gamess/Firefly site, it is stated that negative contributions should be subtracted (http://classic.chem.msu.su/cgi-bin/ceilidh.exe/gran/gamess/forum/?C34df668afbHW-6978-840+00.htm). Can someone help with this? Thanks, Jason ******************************************* Jason D'Acchioli Assistant Professor of Chemistry University of Wisconsin-Stevens Point 2001 Fourth Avenue Stevens Point, WI 54481 http://chemdac.uwsp.edu