From owner-chemistry@ccl.net Fri Oct 26 06:59:00 2018 From: "Tobias Kraemer tobias.kraemer[a]mu.ie" To: CCL Subject: CCL:G: Low-progression Franck-Condon transitions Message-Id: <-53529-181026065741-31274-ZGzAr9KFCM6A7pw5+4lSQQ:-:server.ccl.net> X-Original-From: "Tobias Kraemer" Date: Fri, 26 Oct 2018 06:57:38 -0400 Sent to CCL by: "Tobias Kraemer" [tobias.kraemer_._mu.ie] Hello everyone, I am interested in calculating vibrationally-resolved spectra in G16. The molecule in question is a phthalocyanine (pc) complex. I've followed the protocol detailed in the whitepaper by Barone et al., however in the final step (generating the spectrum) an error occurs: ================================================== Calculations of Band Intensities ================================================== -- To: vibronic fundamental state -- Spectrum progression: 0.06% -- To: single overtones -- Spectrum progression: 0.71% -- To: combinations of 2 simultaneously excited modes -- Spectrum progression: 4.14% ERROR: Low progression after class 2. Total convergence = 4.1%. The vibronic spectrum will likely be unreliable. Stopping. The whitepaper provides some possible causes, but I'd like to ask for some expert opinions here on CCL nonetheless. In the excited state optimisation I have included 6 states, of which the gradients for the first one are to be followed [TD=(Read,NStates=6,Root=1)]. There are a good number of keywords listed on the Gaussian16 webpage that relate to this type of calculation, and I'd appreciate some guidance on the above issue and possible ways around it. Thanks for your help, as always much appreciated. Kind regards, Tobias