CCL:G: Opt with Full point group Symmetry in G09

 Sent to CCL by: "Dillen, Jan [jlmd-$-sun.ac.za]"
 <JLMD-$-sun.ac.za>
 Hi
 Using a Z-matrix for a molecule containing rings is looking for trouble, unless
 you use a so-called "Cartesian" Z-matrix. Also, Gaussian uses
 (internal) redundant coordinates to minimize the energy, unless your override
 that, so all your hard work may be for nothing.
 What is not clear from your question is whether the C2h symmetry structure is an
 energy minimum and why you insist on higher symmetry. I suggest to distort the
 molecule with the eigenvector of the lowest vibrational frequency, and
 minimise/maximise to the nearest stationary point.
 Jan
 -----Original Message-----
 > From: owner-chemistry+jlmd==sun.ac.za^^ccl.net [mailto:owner-chemistry+jlmd==sun.ac.za^^ccl.net] On Behalf Of Mr Mi Yang
 agri_chemist##yahoo.com
 Sent: 28 March 2012 08:19
 To: Dillen, Jan <jlmd^^sun.ac.za>
 Subject: CCL:G: Opt with Full point group Symmetry in G09
 Sent to CCL by: "Mr Mi Yang" [agri_chemist\a/yahoo.com] First of all
 thanks for replies of Jimenez Vazquez, Cory Pye and others.
 Actually, I have used Z-matrix made by molden and it works perfect to maintain
 symmetry in G09 only for small molecules like benzene. But for a Fulleren like
 molecule to build Z-matrix manually is almost impossible.
 Is there any software which can help to build Z-matrix for 3 dimensional
 fulleren like big molecule by using some dummy atoms so that it can maintain
 symmetry in G09 opt...?
 I observed below mentioned problem in most of molecules with DnD or DnH
 symmetries where G09 try to maintain largest Abelian group instead of full point
 group.
 I have not included any diffused function in basis set but will check a bigger
 set without diffused function.
 regards,
 Mr.MiYang
 > "Hugo Alejandro Jimenez Vazquez hjimenez],[woodward.encb.ipn.mx"
 wrote:
 >
 > Sent to CCL by: Hugo Alejandro Jimenez Vazquez
 > [hjimenez,+,woodward.encb.ipn.mx]
 >
 > Although MiYang does not mention it, I would guess that he is using
 > diffuse functions in the basis set employed in his (her?) calculations.
 > I am also trying to do calculations on fullerenes, and I have found
 > that the inclusion of diffuse functions breaks the symmetry of the
 > wavefunction with respect to the symmetry of the molecule under
 > analysis. Gaussian says that "the density has only Abelian
 symmetry"
 > and in an optimization the point group of the molecule changes to that
 > of the density with the corresponding increase in computational cost.
 > I have not found a way to solve this problem other than getting rid of
 > the diffuse functions from the basis set, although I am still looking.
 > I asked for advise from Gaussian, but they could not help me. The
 > problem is not particular to Gaussian 09; previous versions of Gaussian
 also exhibit the same behavior.
 >
 > Another solution would be to use a larger basis set withouth the use
 > of diffuse functions. I have not tried Cory's suggestion though, but I
 > believe that the outcome would be the same.
 >
 > Regards,
 >
 >
 > --
 > ---
 > Hugo A. Jimenez Vazquez
 > hjimenez###woodward.encb.ipn.mx
 > Departamento de Quimica Organica
 > ENCB-IPN
 > Mexico
 >
 >
 >
 > On Tue, 27 Mar 2012, Cory Pye cpye : ap.smu.ca wrote:
 >
 > >
 > > Sent to CCL by: Cory Pye [cpye|,|ap.smu.ca] Hello Mi,
 > >
 > > I recommend the use of opt=z-matrix and a very carefully constructed
 z-matrix.
 > >
 > > -Cory Pye
 > >
 > > On Sun, 25 Mar 2012, Mi Yang agri_chemist%x%yahoo.com wrote:
 > >
 > > >
 > > > Sent to CCL by: "Mi  Yang" [agri_chemist++yahoo.com]
 Dear CCL
 > > > Colleagues, I am desperately trying to optimized a C 40 fulleren
 > > > molecules with D5d symmetry. But after my several calculations
 > > > with different coordinates it reduces the symmetry C2H in final
 > > > geometry. I checked CCL archives and used some helpful keywords
 > > > like symm=loose and iop(2/17=xx),
 > > > iop(2/18=xx) upto 1 etc.
 > > >
 > > > Do Gaussian has ability to optimized only some systems in their
 > > > Largest Abelian subgroup
 instead of
 > > > full point group...?
 > > > In my comparison of systems same point group is necessary so how
 > > > can I optimized the above
 Fulleren
 > > > 40 (D5d) system in G09...?
 > > > Any comment or recommendation will be highly appreciating.....
 > > >
 > > > MiYang>
 > > >
 > >
 > >    *************    !  Dr. Cory C. Pye
 > >  *****************  !  Associate Professor
 > > ***   **    **  **  !  Theoretical and Computational Chemistry
 > > **   *  ****        !  Department of Chemistry, Saint Mary's
 University
 > > **      *  *        !  923 Robie Street, Halifax, NS B3H 3C3
 > > **      *  *        !  cpye]^[crux.stmarys.ca   http://apwww.stmarys.ca/~cpye
 > > ***     *  *    **  !  Ph: (902)-420-5654  FAX:(902)-496-8104
 > >  *****************  !
 > >    *************    !  Les Hartree-Focks (Apologies to Montreal
 Canadien Fans)http://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp-:-//www.ccl.net/chemistry/sub_unsub.shtmlhttp-:-//www.ccl.net/spammers.txtE-pos
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