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Re: [ESPResSo-users] Coulomb forces capping
From: |
Axel Arnold |
Subject: |
Re: [ESPResSo-users] Coulomb forces capping |
Date: |
Fri, 15 Aug 2014 18:27:28 +0400 |
User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 |
Hi!
Capping the Coulomb forces is not possible, since part of them is
long-range, where capping is mathematically extremely difficult. The
same holds for shifting the Coulomb interactions.
We could cap the short-range forces, but then the strength of capping
depends on the tuning of P3M. Such a capping can only be used for warm up.
It might therefore be better to just set up the system from the very
beginning that no overlaps occur, and then equilibrate with full
interactions.
Best,
Axel
On 15.08.14 16:14, Aleksei Kabedev wrote:
Dear all,
I'm not sure that's the best way to do it, but I'm modeling some big
spheres by just central points, giving them LJ potentials and some
charges. The problem is that if the radiuses are too big, I have to
give really big charges to the particles to keep the right surface
charge density, as the potential decreases up to growth of the radius
exponentially. That wouldn't be bad if some overlaps didn't appear
from time to time. In that case even a small intersection causes huge
forces and velocities.
As far as I understood there is no forcecapping for the electrostatic
interaction in espresso. Is there any chance to implement it easily?
Or probably there is a way of shifting the coulomb forces action range?
Thank you!
--
Kind regards,
Aleksei
--
JP Dr. Axel Arnold
ICP, Universität Stuttgart
Allmandring 3
70569 Stuttgart, Germany
Email: address@hidden
Tel: +49 711 685 67609