From owner-chemistry@ccl.net Fri Mar 6 09:06:01 2009 From: "Johannes Hachmann jh388||cornell.edu" To: CCL Subject: CCL:G: G- How to retain the symmetry in a SCF calculation ? Message-Id: <-38772-090306084854-25927-wlj79LMFI3trGquUo5V6aQ..server.ccl.net> X-Original-From: "Johannes Hachmann" Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Date: Fri, 6 Mar 2009 08:48:36 -0500 MIME-Version: 1.0 Sent to CCL by: "Johannes Hachmann" [jh388(0)cornell.edu] Hi John, obviously you are usually interested in the proper electronic ground = state - but being interested in e.g. spin gaps, or a comparison of the = electronic structure/orbital sets of different spin states, or in a = specific starting guess for a post-HF calculation (which happens to be = not the ground state) is not that far fetched... Then it doesn't really = help you if your calc always falls back on the ground state which has a = symmetry that's not of interest for you. Best Johannes=20 --------------------------------------------------------------- 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=3D=3Dcornell.edu(0)ccl.net=20 > [mailto:owner-chemistry+jh388=3D=3Dcornell.edu(0)ccl.net] On Behalf=20 > Of John McKelvey jmmckel__gmail.com > Sent: Thursday, March 05, 2009 12:12 PM > To: Hachmann, Johannes > Subject: CCL:G: G- How to retain the symmetry in a SCF calculation ? >=20 > Is the possibility of finding a symmetry of lower energy _all=20 > that bad_? I can think of an obvious reason why it would be=20 > beneficial.... >=20 > Cheers, >=20 > John McKelvey >=20 >=20 >=20 > On Wed, Mar 4, 2009 at 11:19 PM, Johannes Hachmann jh388 ~~=20 > cornell.edu wrote: >=20 >=20 >=20 > Sent to CCL by: "Johannes Hachmann" [jh388_._cornell.edu] > Hi Ding, > =09 > sorry, never ran into this problem. Note that you might=20 > have to try a number of orbital swaps to get to the=20 > wavefunction irrep you want. Also, in case you use the STABLE=20 > keyword, DO NOT use STABLE=3DOPT because that will likely bring=20 > you back to a more stable wavefunction of different symmetry. > =09 > Hope that helps > =09 > Best > =09 > Johannes > =09 > --------------------------------------------------------------- > Johannes Hachmann > (Dipl.-Chem., M.Sc.) > =09 > Chan Research Group > 140D Baker Laboratory > Department of Chemistry and Chemical Biology > Cornell University > Ithaca, NY 14853-1301 > USA > --------------------------------------------------------------- > =09 > > -----Original Message----- > > From: owner-chemistry+jh388=3D=3Dcornell.edu]|[ccl.net > > [mailto:owner-chemistry+jh388=20 > =3D=3Dcornell.edu]|[ccl.net] On = Behalf > > Of xunlei ding dingxunlei:_:gmail.com > > Sent: Wednesday, March 04, 2009 5:12 AM > > To: Hachmann, Johannes > > Subject: CCL:G: G- How to retain the symmetry in a=20 > SCF calculation ? > > > > > > Sent to CCL by: xunlei ding [dingxunlei|gmail.com]=20 > Dear Johannes, > > > > Sometimes scf=3DQC works but not always. > > I hope there be a better way for this problem. > > > > It seems that we can use IOP, as is described as: > > > > IOp(5/15) > > Apply Abelian symmetry constraints on orbitals. > > > > 0 Default (1 for L502, 2 for L501 and L506). > > 1 No. > > 2 Yes, keep occupation of each irrep the same as the > > initial guess. > > 3 Yes, keep overall wavefunction the same as=20 > the initial guess, > > but doing the minimal amount > > of orbital switching to accomplish this. > > 00 Default (use Abelian symmetry in diagonalization). > > 10 Use Abelian symmetry in diagonalization. > > 20 Do not use Abelian symmetry in diagonalization. > > > > But in my test, iop(5/15=3D2) doesn't work. > > > > Any more suggestions? > > > > Thanks a lot! > > > > Best regards, > > Ding > > > > > > > > 2009/2/13 Johannes Hachmann jh388[*]cornell.edu > > : > > > > > > Sent to CCL by: "Johannes Hachmann"=20 > [jh388!A!cornell.edu] Hi Ding, > > > > > > use SCF=3DQC (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=3DALTER. This is not a > > particularly elegant > > > way to do things (compared to just specifying the=20 > 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 > > > > > >=20 > --------------------------------------------------------------- > > > Johannes Hachmann > > > (Dipl.-Chem., M.Sc.) > > > > > > Chan Research Group > > > 140D Baker Laboratory > > > Department of Chemistry and Chemical Biology=20 > Cornell University > > > Ithaca, NY 14853-1301 USA > > >=20 > --------------------------------------------------------------- > > >> -----Original Message----- > > >> From: owner-chemistry+jh388=3D=3Dcornell.edu[]ccl.net > > >> [mailto:owner-chemistry+jh388=20 > =3D=3Dcornell.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=20 > [dingxunlei.:.gmail.com] Dear CCLers, > > >> > > >> In the manual of G03, the key word "SCF=3D 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=20 > 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 > > >> > > >> > > >> > > >> -=3D This is automatically added to each message by the > > mailing script > > >> =3D- 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> > > >> Conferences: > > >> http://server.ccl.net/chemistry/announcements/conferences/ > > >> > > >> Search Messages: http://www.ccl.net/htdig (login: ccl, > > >> Password: search)> > > >> > > > > > > > > > > > > -=3D This is automatically added to each message by the > > mailing script > > > =3D-> Search Messages: http://www.ccl.net/htdig (login: ccl, > > Password: > > > search)> > > > > > > > > > > > > > > -- > > ------------------------------------------------------ > > Xun-Lei Ding > > Associate Research Professor of Physical Chemistry State Key > > Lab for Struct. Chem. of Unstable and Stable Species > > Institute of Chemistry, The Chinese Academy of Sciences > > Zhongguancun North First Street 2=EF=BC=8C > > Beijing 100190, P. R. 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