[gmx-users] Why density increase with increasing the cutoff length?

[David van der Spoel]

On 12/21/09 8:03 AM, Yanmei Song wrote:
> Dear Users:
>
> Anyone can explain why the density of the water models increase with
> increase the cutoff length. I tried a couple water models in
> reaction-field, PME simulations.The cutoff length ranged from 0.9 to
> 1.5. They all show the same trend. Then there must be some reasons.
> Anyone can tell me why?
>
> --
> Yanmei Song
> Ph.D. Candidate
> Department of Chemical Engineering
> Arizona State University
>
Van der Waals interactions. I guess you have not turned on the 
dispersion correction. If you do the effect should be far less.

-- 
David van der Spoel, Ph.D., Professor of Biology
Molec. Biophys. group, Dept. of Cell & Molec. Biol., Uppsala University.
Box 596, 75124 Uppsala, Sweden. Phone:	+46184714205. Fax: +4618511755.
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://folding.bmc.uu.se