Re: PMEGridSize and parameters controlling electrostatic interactions.

From: Maxim Belkin (mbelkin_at_ks.uiuc.edu)
Date: Sat Jan 24 2015 - 14:11:59 CST

Yes, use PMEGridSpacing 1.0.

Maxim

> On Jan 24, 2015, at 13:48, Dawid das <addiw7_at_googlemail.com> wrote:
>
> Dear NAMD experts,
>
> I was doing MD simulation on a small system and I used following parameters:
>
> Pme on
> PmeGridSizeX 48
> PmeGridSizeY 48
> PmeGridSizeZ 96
>
> switching on
> switchDist 10
> cutoff 12
> pairlistdist 14
> margin 3
>
> Everything went fine, until I made my system bigger, so I had to change PME grid sizes to:
>
> PmeGridSizeX 96
> PmeGridSizeY 96
> PmeGridSizeZ 244
>
> Now when I try to heat up my system I get following error at 116 K:
>
> FATAL ERROR: Low global exclusion count! (1086603 vs 1086604) System unstable or pairlistdist or cutoff too small.
>
> So my question is if there is any relationship between PmeGridSize and electrostatic parameters values in a sense that I should change the latter in this case?
> Or perhaps I shall not increase PmeGridSize, but PMEGridSpacing instead?
>
> Best wishes,
>
> Dawid Grabarek

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