From owner-chemistry@ccl.net Thu Nov 10 13:31:00 2011 From: "David N Bowman dnbowman!^!ncsu.edu" To: CCL Subject: CCL:G: G09:Reproducing vibrationally resolved photodetachment spectrum of SF6 Message-Id: <-45865-111110121725-17744-HkmEub7IhojocbVikFbplg/a\server.ccl.net> X-Original-From: "David N Bowman" Date: Thu, 10 Nov 2011 12:17:22 -0500 Sent to CCL by: "David N Bowman" [dnbowman=-=ncsu.edu] Dear All, I am trying to reproduce the vibrationally resolved photodetachment spectrum of SF6- found in the following articles: (1) Fully Integrated Approach to Compute Vibrationally Resolved Optical Spectra: From Small Molecules to Macrosystems, http://pubs.acs.org/doi/abs/10.1021/ct8004744 (section 4.2) and, (2) Vibrationally-resolved electronic spectra in GAUSSIAN 09, idea.sns.it/files/idea/docs/vibronic_spectra_G09-A02.pdf (section 5). I have performed the calculation by following the 3-step procedure described in (2) as follows: 1. Calculate frequencies for initial state 2. Calculate frequencies for final state 3. Generate electronic spectra Here are my input files, all of which are in separate folders: (Contents of SF6_neut.com) %chk=SF6_neut.chk #p opt(CalcFC) freq=SaveNormalModes mp2/aug-cc-pvtz NoSymm [S(F)6]0 0 1 16 0.000000 0.000000 0.000000 9 0.000000 0.000000 1.575064 9 0.000000 0.000000 -1.575064 9 0.000000 1.575071 0.000000 9 0.000000 -1.575071 0.000000 9 1.575149 0.000000 0.000000 9 -1.575149 0.000000 0.000000 (EOF) (Contents of SF6_anion.com) %chk=SF6_anion.chk #p opt(CalcFC) freq=SaveNormalModes mp2/aug-cc-pvtz NoSymm [S(F)6]- -1 2 16 0.000000 0.000000 0.000000 9 0.000000 0.000000 1.714498 9 0.000000 0.000000 -1.714498 9 0.000000 1.714569 0.000000 9 0.000000 -1.714569 0.000000 9 1.714577 0.000000 0.000000 9 -1.714577 0.000000 0.000000 (EOF) (Contents of SF6_neut.com for final spectrum generation) %chk=SF6_neut.chk #p Geom=AllCheck Freq=(ReadFC,FC,SaveNM,ReadFCHT) NoSymm PRTMAT=12 MAXC1=100 MAXBANDS=4 SPECHWHM=0.5 SF6_anion.chk (EOF) So, when I run the final step to generate the spectrum I get the following: "ERROR: The Franck-Condon factor corresponding to the overlap integral between both vibrational ground states is too small: |<0'|0">|^2 < 0.81455E-10." I can force the calculation to run using the ForceFCCalc keyword, however, when I do this I get a spectrum that is nothing like that shown in figure 2 of (1). Any advice would be greatly appreciated. Thanks, David N. Bowman Chemistry Department North Carolina State University