From owner-chemistry-!at!-ccl.net Tue Jun 26 11:00:01 2007 From: "errol lewars elewars%a%trentu.ca" To: CCL Subject: CCL: UV-Vis calculations Message-Id: <-34572-070626103104-14718-x5iIhITaPHWx/apxg83acA|*|server.ccl.net> X-Original-From: errol lewars Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1; format=flowed Date: Tue, 26 Jun 2007 09:36:46 -0400 MIME-Version: 1.0 Sent to CCL by: errol lewars [elewars:trentu.ca] 2007 June 26 I don't know what your results for biphenyl look like, but TDDFT or CIS calculations could easilily be out by 20 nm or so, and signals of zero oscillator strength actually show up in the experimental UV as weak absorptions, because of vibrational distortions from perfect symmetry. To get a feel for this do some calculations on small molecules and compare the calculated and exp UVs. The "solution" to your problem is to be allow for the errors in the calculations. E. Lewars === Pedro David Ortiz pedrod-$-fq.uh.cu wrote: >Sent to CCL by: "Pedro David Ortiz" [pedrod/./fq.uh.cu] >Dear CCL: > >Im trying to do UV-Vis calculations of C6H5-C6H5 by using DFT TD and CIS. I have obteined very but results with bouth methods: in the range of energy corresponding to experimental absortion there are not signals with significat oscilator strength. All comments about solutions will be very appreciated. > >Thanks in advance.> > > > >