Subject: Re: CCL:system size and pressure correlations in MD

From: "David A. Case" <[email-masked]>
Date: Fri, 21 Feb 2003 23:48:43 -0800

On Thu, Feb 20, 2003, M Brunsteiner wrote:
> 
> I am looking for information on pressure 
> correlations in liquds. If I did a molecular 
> dynamics simulation, how would the size of the 
> pressure fluctuations depend on the system size
> (the box-size in an MD simulation) 

The simplest place I know to look for information on this is section 114
of "Statistical Physics", by Landau and Lifshitz.  With some (seemingly
reasonable) approximations, the mean square fluctuations in pressure
are given by kT/(V*beta), where beta is the compressibility.  Hence,
roughly, the pressure fluctuations should scale as the inverse square
root of the volume.  Many moons ago, I ran some water simulations on various
box sizes, that seemed to bear this out, but you should probably check things
yourself.

..hope this helps...dac

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David A. Case                     |  e-mail:      [email-masked]
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