From owner-chemistry:~at~:ccl.net Wed Oct 19 05:07:01 2005
From: "andras.borosy+*+givaudan.com" <owner-chemistry;;server.ccl.net>
To: CCL
Subject: CCL: constrained geometry optmisation of molecular complexes
Message-Id: <-29653-051019050439-20727-gJKokDZHWSap5rm98+rrIw;;server.ccl.net>
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Date: Wed, 19 Oct 2005 11:04:03 +0200
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Sent to CCL by: andras.borosy|,|givaudan.com
Dear James,

You may try semi-empirical methods as this has been done in the following 
articles:

Timothy J. Giese, Edward C. Sherer, Christopher J. Cramer, and Darrin M. 
York, A Semiempirical Quantum Model for Hydrogen-Bonded
Nucleic Acid Base Pairs, J. Chem. Theory Comput. (published in web in 
September 2005).

E. NIKITINA, V. SULIMOV, V. ZAYETS, N. ZAITSEVA, International Journal of 
Quantum Chemistry, Vol 97, 747–763 (2004).

Best wishes,

Dr. András Borosy
Seniour Scientist
Delivery Systems, Fragrance Research
Givaudan Schweiz AG
Ueberlandstr. 138
8600 Dübendorf
Switzerland
tel: + 41-1-8242164
fax: +41-1-8242926
e-mail: andras.borosy-#-givaudan.com

owner-chemistry-#-ccl.net wrote on 10.10.2005 19:54:09:

> 
> Sent to CCL by: Andreas Serr [serr/a\theorie.physik.uni-muenchen.de]
> Dear James,
> 
> sorry I cannot answer your questions, but I would like to make a 
> short comment on 
> 
> >  So far as I understand, HF 
> > methods, semi-empirical methods and most DFT functionals will not 
> > describe van-der-Waals forces (responsible for a good part of the 
> > non-binding interaction?) correctly.
> 
> A standard HF or DFT calculation *does* incorporate Keesom and Debye
> interactions (dipole-dipole, dipole-induced dipole) -- it will simply be
> reflected in charge re-distributions of the molecules.
> 
> You are right that they do *not* account for London (dispersion) 
interaction
> (induced dipole-induced dipole).
> 
> Depending on your system (mainly: magnitude of static dipole) either 
Keesom,
> Debye or London interact. may dominate van-der-Waals forces.
> 
> Sorry again, if it does not help for your question.
> 
> Regards,
> Andreas
> 
> 
> Andreas Serr
> 
> Biological Soft-Matter Theory
> Sektion Physik - Ludwig-Maximilians-Universitaet
> Theresienstr. 37, D-80333 Munich, Germany
> tel: +49-(0)89-2180-4603 / fax: +49-(0)89-2180-4517
> room no: 304 / e-mail: serr*theorie.physik.uni-muenchen.de
> http://www.theorie.physik.uni-muenchen.de/biophysics/> 
>