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[ESPResSo-users] Re: Time step question

From: Ulf Schiller
Subject: [ESPResSo-users] Re: Time step question
Date: Fri, 18 Mar 2011 09:57:26 +0100
User-agent: Thunderbird (X11/20100302)


Michael Winokur wrote:
> So after letting my Espresso project lay idle for awhile I've picked up
> the pieces of a connected Gay-Berne particle interaction simulation.
> Briefly: I'm in the process of tuning the time stepping to prevent
> unphysical results.  I immediately noticed that after halving the time
> step the simulation's average kinetic energy per particle actually
> dropped even though I kept the temperature set point constant.  I
> haven't looked into the source code but this suggests something isn't
> quite right.

What kind of thermostat are you using?

> Does anyone have any suggestions as to how I should go about trouble
> shooting this?

I'd suggest testing with a single particle whether the
fluctuation-dissipation relation checks out. Then with two particles,
and so on. This will tell you whether it is an issue with the thermostat
or the particle interaction.


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