[gmx-users] NVE simulations

[David L. Bostick]

It all depends on that initial configuration and velocities for an NVE
simulation.  The total energy can remain the same while the temperature
drops.  This is why in the old days people used to scale their velocities
each step for some time before actually simulating the system.  You can try
equilibrating the system in NVT and then change to NVE with initial
coordinates and velocities taken from the last snapshot of the NVT
simulation.

Generally, if the initial configuration is energetically high, the
temperature will go through the roof.  If it is very low, the potential at
the starting point will be turned into kinetic energy plus whatever
velocities you add in the beginning using the velocity generation option
and the temperature can still fall.

David

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David Bostick					Office: 262 Venable Hall
Dept. of Physics and Astronomy			Phone:  (919)962-0165
Program in Molecular and Cellular Biophysics
UNC-Chapel Hill
CB #3255 Phillips Hall				dbostick at physics.unc.edu
Chapel Hill, NC 27599	           		http://www.unc.edu/~dbostick
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On Mon, 8 Jul 2002, Sidney Elmer wrote:

> Hi,
>
> I have a question about the pure MD (constant NVE) application.
> Whenever I try to run my system at constant Energy, the system always
> cools down to zero temperature.  Instead of being a constant energy
> simulation, it appears rather that it is a variant of an energy
> minimization.  Has anyone else had this happen to them? or is there
> something that I am missing in my parameter file?  Thanks.
>
> Sid
>
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