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

[Yanmei Song]

Thanks for all the helpful response. But do I have to use dispersion
correction when I use PME? I don't quite understand what dispersion
correction do. Sometime I found using dispersion correction make my results
worse for a large molecule system.

On Mon, Dec 21, 2009 at 12:48 AM, David van der Spoel
<spoel at xray.bmc.uu.se>wrote:

> 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
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-- 
Yanmei Song
Ph.D. Candidate
Department of Chemical Engineering
Arizona State University
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