Re: Vaccum simulation

Date: Wed Dec 08 2004 - 15:57:10 CST

There is no intrinsic temperature limit, but at some point, as you raise the
temperature (which means increasing the particle kinetic energies and thus
their velocities) you will encounter problems with the integration routine
breaking down.

However, you should be able to handle this simply by reducing the size of
the 'timestep' parameter at higher temps. The typical value of 1.0fs is
for room temp, but wouldn't work so well at much higher temps. This problem
will be even more apparent if you have unconstrained hydrogen atoms in your
system. (since they have much higher velocities than other atoms at a given

Hope this helps!

C. Erik Nordgren, Ph.D.
Department of Chemsitry
University of Pennsylvania

Quoting Narender Singh <>:

> Hi, i am trying to do vaccum simulation of a membrane protein (with the
> aim of totally 'unfolding' the protein) at high temperature but the
> system
> is not able to go beyond 600K and keep exiting due to velocity-limit
> error(after few thousand steps). Is 600K the temperature limit of NAMD?
> Any idea/way on how can i achive my aim?
> Thank you
> NS

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