Re: question about NPT

From: Axel Kohlmeyer (
Date: Thu Jan 19 2012 - 05:14:04 CST

On Jan 19, 2012, at 3:16 AM, Boyang Wang <> wrote:

Hi Oguz,

pressure fluctuates a lot in NPT ensemble, because the volume fluctuates a
lot. If you would like

This is nonsense. The volume does *not* fluctuate a lot, it is the low
compressibility of dense fluids that causes the relatively high pressure


smaller fluctuation of pressure, you can increase the Langevin piston's
mass in the configuration file.


On Wed, Jan 18, 2012 at 4:06 PM, oguz gurbulak <>wrote:

> Dear All,
> I performed md simulations in NPT ensamble and got -1000 atm pressure
> value for the system. My aim is to find 1 atm pressure value instead of a
> negative pressure value. Is this problem indicates that the force field
> I use is not appropriate for my system ? or Is this a problem caused by the
> langevin parameters ?
> why the system did not reach the target pressure value? Could you please
> share your thoughts about this problem ?
> Kind regards.

Boyang Wang, Ph.D.

This archive was generated by hypermail 2.1.6 : Tue Dec 31 2013 - 23:21:35 CST