From owner-chemistry@ccl.net Sun Apr 21 04:24:01 2019 From: "Frank Jensen frj{:}chem.au.dk" To: CCL Subject: CCL:G: SV: CCL:G: Minimum energy crossing point MECP Message-Id: <-53697-190421042230-5456-Za+0oVTdWcTMzS+24mRiGw{}server.ccl.net> X-Original-From: Frank Jensen Content-Language: da-DK Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="iso-8859-1" Date: Sun, 21 Apr 2019 08:22:20 +0000 MIME-Version: 1.0 Sent to CCL by: Frank Jensen [frj(~)chem.au.dk] Actually, Gaussian can do MECP, by selecting the proper roots in a CASSCF calculation in a Slater Determinant basis, where both singlet and triplet states are present. Gamess can do this as well, using an effective gradient algorithm. In our experience, this may not be the most stable algorithm. We have implemented both a penalty and a Lagrange-Newton algorithm in Gamess, and the latter is in our hands the most stable and versatile algorithm. Frank Frank Jensen Assoc. Prof. Dept. of Chemistry Aarhus University https://tildeweb.au.dk/au23758/ -----Oprindelig meddelelse----- Fra: owner-chemistry+frj==chem.au.dk#ccl.net På vegne af Eric V. Patterson eric.patterson===stonybrook.edu Sendt: 20. april 2019 22:16 Til: Frank Jensen Emne: CCL:G: Minimum energy crossing point MECP Sent to CCL by: "Eric V. Patterson" [eric.patterson=stonybrook.edu] I do not believe Gaussian can do this automatically. IIRC, the conical intersection / avoided crossing capability in Gaussian requires both states to have the same spin. You could search manually by performing a series of constrained optimizations along the reaction pathway with both spin states. Alternatively, you could use GAMESS. The MEX feature in GAMESS will do exactly what you want. I have used it with some success. Cheers, Eric > On Apr 20, 2019, at 9:00 AM, Benoit Gearald ablux13,+,gmail.com wrote: > > > Sent to CCL by: "Benoit Gearald" [ablux13 _ gmail.com] Dear CCLers, > > Could you please inform me about the way to find the minimum energy > crossing point (MECP) on conical intersect for Spin-forbidden > reactions > (radicals) using Gaussian 09? > > I would like to find it for passage from the triplet to the singlet > intermediate. > > Regards, > > Benoithttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txt