From owner-chemistry@ccl.net Sun Aug 17 09:40:00 2008 From: "gnli gnli(-)dicp.ac.cn" To: CCL Subject: CCL:G: Singlets or Triplets ? Message-Id: <-37572-080817093748-592-iekOJY43JXBWhoLZsgeQCw##server.ccl.net> X-Original-From: "gnli" Content-Type: multipart/alternative; boundary="----=_NextPart_000_0000_01C900B1.B3A3D600" Date: Sun, 17 Aug 2008 21:39:16 +0800 MIME-Version: 1.0 Sent to CCL by: "gnli" [gnli]_[dicp.ac.cn] This is a multi-part message in MIME format. ------=_NextPart_000_0000_01C900B1.B3A3D600 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Dear CCLer, I have a question about using the keyword TD in Gaussian to calculate UV-vis spectra: there are three options, singlets, triplets and 50-50. When calculate the excited states, which I need to choose? or just use the default set ? Thank you ! best wishes Guanna Li gnli/./dicp.ac.cn ------=_NextPart_000_0000_01C900B1.B3A3D600 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Dear = CCLer,

I have a question about = using the keyword TD in Gaussian to calculate UV-vis spectra: there are three = options, singlets, triplets and 50-50.

When calculate the excited = states, which I need to choose? or just use the default set ? =

Thank you = !

best wishes
Guanna Li
gnli/./dicp.ac.cn



 

------=_NextPart_000_0000_01C900B1.B3A3D600-- From owner-chemistry@ccl.net Sun Aug 17 13:17:00 2008 From: "William F. Coleman wcoleman#wellesley.edu" To: CCL Subject: CCL: Singlets or Triplets ? Message-Id: <-37573-080817131225-20020-cQh0tjDwxnUX350HDx7A/w:-:server.ccl.net> X-Original-From: "William F. Coleman" Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Date: Sun, 17 Aug 2008 13:03:36 -0400 MIME-Version: 1.0 Sent to CCL by: "William F. Coleman" [wcoleman%%wellesley.edu] "CCL Subscribers" on Sunday, August 17, 2008 at 9:39 AM -0400 wrote: >When calculate the excited states, which I need to choose? or just use >the default set ? In a lot of ways, the answer to your question depends on what it is you want to know. Assuming your ground state is a singlet, and you wish to predict major spectral features (those with moderate to large oscillator strengths, you want to do singlets only. If you are trying to predict phosphorescence, or locate weak spin-forbidden transitions, then you want some triplets as well. Cheers, Flick Coleman _______________ William F. Coleman Professor of Chemistry Wellesley College Wellesley MA 02481 on leave 2007-08 - please contact via email only wcoleman~!~wellesley.edu www.wellesley.edu/Chemistry/colemanw.html Editor, JCE WebWare and JCE Featured Molecules http://www.jce.divched.org/JCEDLib/WebWare/ http://jchemed.chem.wisc.edu/JCEWWW/Features/MonthlyMolecules/index.html