On Mon, Nov 14, 2011 at 11:29 AM, Ismail, Mohd F. <farid.ou.edu> wrote:
> Dr. Roitberg,
>
> I'm sorry, I meant to say it converged to the wrong value, i.e. it is off by a few percent (varies depending on the solvent) from the experimental value.
>
> Dr. Chaban,
>
> What I am wondering is, is this acceptable to use differing methods for the different parameters?
It is what is everywhere done... My opinion that this is not a taboo
as well as it is not an exact physics. If you want a very clear
derivation of the FF, than you should accept 3% difference in density.
>Is there a paper that describes how to change vdw?
Search for the "force field" in the titles of the papers. You will get
a plenty of examples how people do this. Quite often, they just change
VDW with the only argumentation "to get a better coincidence with
experiment". I don't like this way, so I suggested you to play with
electrostatics.
If you describe your particular system, we may be able to provide
better suggestions for that case.
--
Dr. Vitaly V. Chaban, 430 Hutchison Hall, Chem. Dept.
Univ. Rochester, Rochester, New York 14627-0216
THE UNITED STATES OF AMERICA
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Received on Mon Nov 14 2011 - 10:30:03 PST
