From owner-chemistry ":at:" ccl.net Wed Mar 28 02:20:01 2012
From: "Mr Mi Yang agri_chemist##yahoo.com" <owner-chemistry a server.ccl.net>
To: CCL
Subject: CCL:G: Opt with Full point group Symmetry in G09
Message-Id: <-46578-120328021847-17067-/jgHoIzzWk9UoKMjo01e8g a server.ccl.net>
X-Original-From: "Mr Mi Yang" <agri_chemist%yahoo.com>
Date: Wed, 28 Mar 2012 02:18:44 -0400


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)
> >
> 
>