AMBER Archive (2002)

Subject: Re: convergence of MD simulations

From: darden (darden_at_gamera.niehs.nih.gov)
Date: Mon Apr 08 2002 - 15:08:10 CDT

Dear sue
sorry no one seems to have replied yet. actually in nve the ratio you
want is RMS(PE+KE)/RMS(KE) i.e. ratio of fluctuation in total energy (that
which is to be conserved) to the kinetic or potential energy fluctuations.
The way we do NTP simulations there is currently no corresponding measure
of quality. Maybe someday we'll implement one of the fancier Lagrangian
based approaches to NTP, which will involve a generalized energy that gets
conserved. But this is not imminent as far as I know.
Hope this helps
Tom Darden
 On Thu, 4 Apr 2002, Sue Heavner wrote:

> Dear Amber users:
> I posted the following question to the reflector several days ago, having received no responses I thought I would
> try again. Any thoughts on this would be greatly appreciated.
>
> I read that in NVE simulations, the ratio of RMS fluctuations of the potential and kinetic energies is an indication
> of convergence of energy, with RMS(PE)/RMS(KE) = 0.01 indicating a satisfactory level of global energy
> stabilization. Is there such a test for NTP simulations?
> Thanks in advance, Sue Heavner
>