Re: How to maintain Density constant?

From: Ivan Gregoretti (
Date: Thu Mar 06 2014 - 07:23:29 CST

Hello Roy,

My interpretation of Kenno's link to a wiki with the most fundamental
concepts of thermodynamics is his way of saying that

p V = n R T

with n being the number of molecules and V being volume. It's an ideal
gas state equation. Notice that n/V is your density.

In your molecular dynamics, n does not change, so, if you want to keep
the density constant, you need to run your simulation at constant

Do I get it right Kenno?

In the "NAMD TUTORIAL" pdf, section 1.7.1, find the part that talks
about the NVT esemble. The tutorial is a companion to a group of files
from a molecular dynamics course or workshop. You should be able to
find the example configuration file there.

I hope I am being useful.


Ivan Gregoretti, PhD

On Wed, Mar 5, 2014 at 5:51 PM, Kenno Vanommeslaeghe
<> wrote:
> On 03/05/2014 04:43 PM, Roy Fernando wrote:
>> I appreciate any advise/suggestion.
> My advice is to pick up a basic thermodynamics textbook.

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