From owner-chemistry@ccl.net Thu Mar 17 18:59:00 2016 From: "Susi Lehtola susi.lehtola\a/alumni.helsinki.fi" To: CCL Subject: CCL:G: regarding excited state optimization Message-Id: <-52117-160317151746-31563-gXMCZzLqInrV/UxsagF+ow(~)server.ccl.net> X-Original-From: Susi Lehtola Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=utf-8; format=flowed Date: Thu, 17 Mar 2016 12:17:33 -0700 MIME-Version: 1.0 Sent to CCL by: Susi Lehtola [susi.lehtola . alumni.helsinki.fi] On 03/16/2016 11:19 PM, navjot navu1989mann(_)gmail.com wrote: > Respected sir, > I am working with vanadium oxide clusters. V4O10 cluster in its > ground state optimized by using TZVP/B3LYP in gaussian 09 suit of > program. Now, I want to optimize first excited state of V4O10 cluster. I > had already tried by using TDSCF and CIS but my job didn"t get converge. > Further by using this excited state i need to explore the PES for > reaction of V4O10 +C6H6. Please help to to give proper input for this > job.. I shall be very thankful for this act of kindness. I'm betting the reason why you get the convergence problems is that it's a transition metal oxide system. These tend to be extremely tricky due to strong correlation. Now, you're trying to model it with a single-reference method, which typically have a swath of local solutions for the ground state, and convergence is terribly poor. Also, because of the similarity of CIS to stability analysis, I bet you'd find negative excitation energies in the calculation. You might have much better luck getting the runs to converge using pure DFT, even just the LDA might be the most accurate functional for these systems... -- ----------------------------------------------------------------------- Mr. Susi Lehtola, PhD Chemist Postdoctoral Fellow susi.lehtola-.-alumni.helsinki.fi Lawrence Berkeley National Laboratory http://www.helsinki.fi/~jzlehtol USA -----------------------------------------------------------------------