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Re: [ESPResSo-devel] Nsquare cellsystem and folded positions
From: |
Axel Arnold |
Subject: |
Re: [ESPResSo-devel] Nsquare cellsystem and folded positions |
Date: |
Mon, 13 Aug 2007 16:38:11 +0200 |
User-agent: |
KMail/1.8.2 |
On Monday 13 August 2007 16:26, Olaf Lenz wrote:
> Axel Arnold wrote:
> > Why not????? For forces, energy etc. the distances are correctly folded,
> > as far as I can remember.
>
> Hmm, apparently you are not of the same opinion as Hanjo in that
> respect. However, my tests showed that at least for constraints, the
> force computation does not work correctly. I'll provide an example
> script soon.
Ok, to clarify that: The pair forces use the minimum image distance, both in
domdec and nsquare. For the constraint forces, for some reason we use the
internally folded coordinates. That can indeed cause a problem, but actually
for both cellsystems. E.g. consider an excluded sphere close to the boundary.
Again, the example:
setmd box_l 5 5 5
part 0 pos 0 0 0 v -0.1 0 0
inter 0 0 lennard-jones 1.0 1.0 1.12246 0.25 0
constraint sphere center 4 0 0 radius 1 direction outside type 0
setmd time_step 0.01
thermostat off
setmd skin 1
for {set i 0} {$i < 100} {incr i} {
integrate 10
puts [part 0 pr folded]
}
The particles goes unperturbed right into the sphere, then gets folded, and
Espresso crashes :). And that is domaindecomposition.
So, we have a bug treating constraints, but that actually applies to all
cellsystems.
Axel
--
Dr. Axel Arnold
FOM Institute for Atomic and Molecular Physics
Kruislaan 407 Phone: +31 20 6081 275
1098 SJ Amsterdam, The Netherlands E-mail: address@hidden
- Re: [ESPResSo-devel] Nsquare cellsystem and folded positions, (continued)
Re: [ESPResSo-devel] Nsquare cellsystem and folded positions, Axel Arnold, 2007/08/13
- Re: [ESPResSo-devel] Nsquare cellsystem and folded positions, Olaf Lenz, 2007/08/13
- Re: [ESPResSo-devel] Nsquare cellsystem and folded positions, Axel Arnold, 2007/08/13
- Re: [ESPResSo-devel] Nsquare cellsystem and folded positions, Kai Grass, 2007/08/13
- Re: [ESPResSo-devel] Nsquare cellsystem and folded positions, Olaf Lenz, 2007/08/13
- Re: [ESPResSo-devel] Nsquare cellsystem and folded positions, Axel Arnold, 2007/08/13
- Re: [ESPResSo-devel] Nsquare cellsystem and folded positions, Olaf Lenz, 2007/08/13
- Re: [ESPResSo-devel] Nsquare cellsystem and folded positions,
Axel Arnold <=
- [ESPResSo-devel] Cellsystem, folded position, constraints (was: Nsquare cellsystem and folded positions), Ulf Schiller, 2007/08/13
- Re: [ESPResSo-devel] Cellsystem, folded position, constraints, Olaf Lenz, 2007/08/13
- Re: [ESPResSo-devel] Nsquare cellsystem and folded positions, Olaf Lenz, 2007/08/13
- Re: [ESPResSo-devel] Nsquare cellsystem and folded positions, Kai Grass, 2007/08/13
- Re: [ESPResSo-devel] Nsquare cellsystem and folded positions, Axel Arnold, 2007/08/13
- Re: [ESPResSo-devel] Nsquare cellsystem and folded positions, Olaf Lenz, 2007/08/13
- RE: [ESPResSo-devel] Nsquare cellsystem and folded positions, Limbach, Hans Joerg, LAUSANNE, NRC-FS, 2007/08/14