Subject: Re: CCL:universal L-J parameters"

From: Anton Feenstra <feenstra*at*chem.vu.nl>
Date: Fri, 04 Jun 2004 18:19:14 +0200

Karin Gutkowski wrote:

> I would like to ask you for help for the following issue:
> 
> I need to use Lenanrd jones molecular parameters (sigma and e/k) in 
> order to adjust my program to the Henry constant, for systems with 
> the following molecules:
> methane
> carbon dioxide
> CO
> N2
> O2
> CH3OH
> C2H5OH
> 
> I found already some values for the LJ parameters, but they vary a 
> lot depending on the reference. So I would like to have the whole 
> information from only one source.

Unfortunately, LJ params are always a property of the atom *pair* under
consideration, which in turn is influenced by the molecules in your
system. In practice, however, you may get away with fewer parameters,
and/or use combination rules. Try any of the biomolecular forcefields
(Gromos, OPLS, Charmm, Amber), they will have at least many molecules
and building blocks similar to those you list.
The Gromos and OPLS ff's are implemented in Gromacs, which I use a lot
so I know the website: www.gromacs.org (and it's free). Beware that
some ff's will list parameters in c6/c12 in stead of sigma/epsilon.

-- 
Groetjes,

Anton
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|             |                                                       |
|  _   _  ___,| K. Anton Feenstra                                     |
| / \ / \'| | | Dept. of Pharmacochem. - Vrije Universiteit Amsterdam |
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