From owner-chemistry@ccl.net Fri Feb 13 10:40:01 2009 From: "Johannes Hachmann jh388[*]cornell.edu" To: CCL Subject: CCL:G: G- How to retain the symmetry in a SCF calculation ? Message-Id: <-38610-090213090426-21813-IswKAodyLVcrj0lj7gdZkg/a\server.ccl.net> X-Original-From: "Johannes Hachmann" Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii" Date: Fri, 13 Feb 2009 09:03:24 -0500 MIME-Version: 1.0 Sent to CCL by: "Johannes Hachmann" [jh388!A!cornell.edu] Hi Ding, use SCF=QC (however quadratically convergent SCF is a bit costy...). See description under http://www.gaussian.com/g_ur/k_guess.htm on the bottom together with GUESS=ALTER. This is not a particularly elegant way to do things (compared to just specifying the state symmetry in e.g. MOLPRO) but it works. You might want to use the STABLE option so that you know whether you have instabilities to which other states and which additional MO swaps you might want to perform. Best Johannes --------------------------------------------------------------- Johannes Hachmann (Dipl.-Chem., M.Sc.) Chan Research Group 140D Baker Laboratory Department of Chemistry and Chemical Biology Cornell University Ithaca, NY 14853-1301 USA --------------------------------------------------------------- > -----Original Message----- > From: owner-chemistry+jh388==cornell.edu,,ccl.net > [mailto:owner-chemistry+jh388==cornell.edu,,ccl.net] On Behalf > Of xunlei ding dingxunlei::gmail.com > Sent: Friday, February 13, 2009 3:42 AM > To: Hachmann, Johannes > Subject: CCL:G: G- How to retain the symmetry in a SCF calculation ? > > > Sent to CCL by: xunlei ding [dingxunlei.:.gmail.com] Dear CCLers, > > In the manual of G03, the key word "SCF= Symm" is discribed as below: > Retain all symmetry constraints: make the number of occupied > orbitals of each symmetry type (abelian irreducible > representation) match that of the initial guess. Use this > option to retain a specific state of the wavefunction > throughout the calculation. It is the default only for GVB > calculations. > > But sometimes it doesn't work and the last state is different > from the initial state. > > Could you give me more suggestions on how to retain the > symmetry in a SCF calculation? > > Thanks! > > Best regards, > Ding > > > > -= This is automatically added to each message by the mailing > script =- To recover the email address of the author of the > message, please change the strange characters on the top line > to the ,, sign. You can also look up the X-Original-From: line > in the mail header.> Conferences: > http://server.ccl.net/chemistry/announcements/conferences/ > > Search Messages: http://www.ccl.net/htdig (login: ccl, > Password: search)> >