[ESPResSo-users] Re: Time step question

[Ulf Schiller]

Michael,

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.

Cheers,
Ulf

--
Dr. Ulf D. Schiller                         Building 04.8, Room 231a
Institute of Complex Systems (ICS-2)        Phone:  +49 2461 61-1765
Forschungszentrum Jülich, Germany           Fax:    +49 2461 61-2850


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