From chemistry-request@server.ccl.net Wed Jun 21 14:45:35 2000 Received: from ucidoor.unitedcatalysts.com ([208.23.162.2]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id OAA08579 for ; Wed, 21 Jun 2000 14:45:34 -0400 Received: by ucidoor.unitedcatalysts.com; (8.8.8/1.3/10May95) id OAA30225; Wed, 21 Jun 2000 14:51:20 -0400 (EDT) Received: from 10.1.0.50 by ucismtp02.unitedcatalysts.com (InterScan E-Mail VirusWall NT); Wed, 21 Jun 2000 14:42:56 -0400 (Eastern Daylight Time) Received: from lvlxch01.unitedcatalysts.com ([10.1.0.88]) by lvlmail.unitedcatalysts.com (PMDF V5.2-32 #33820) with ESMTP id <0FWI00I4IPLHWR@lvlmail.unitedcatalysts.com> for chemistry@ccl.net; Wed, 21 Jun 2000 14:48:53 -0400 (EDT) Received: by LVLXCH01 with Internet Mail Service (5.5.2650.21) id ; Wed, 21 Jun 2000 14:43:41 -0400 Content-return: allowed Date: Wed, 21 Jun 2000 14:43:40 -0400 From: "Shobe, Dave" Subject: color prediction To: "'CCL'" Message-id: <157A51F55AAAD3119CD70008C7B1629D6383AF@LVLXCH01> MIME-version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) Content-type: text/plain; charset="iso-8859-1" What calculations are necessary to predict the color of an organic pigment or a transition metal complex? This has several subquestions, including: 1. What level of theory is needed to get accurate electronic excitation energies? I suppose this differs for organic and inorganic chromophores. 2. Is the electronic excitation energy pretty much equal to lambda-max, after the usual unit conversions? Or do factors like vibrational coupling come into play in a big way? 3. To predict color you would need the entire absorption-vs.-wavelength plot, not just the lambda-max. How does one get that? 4. Once one has such a plot, how does one convert into a perceived color? How does this interact with lighting conditions? --David Shobe P.S. If any of you has usenet access (I don't), the last question might be more appropriate for sci.engr.color than here. So feel free to forward it there.