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Date: Thu, 23 May 2002 08:14:15 -0400
From: Richard Gillilan <reg8 |-at-| cornell.edu>
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To: Hannes Loeffler <Hannes.Loeffler.,at,.uibk.ac.at>
CC: chemistry "-at-" ccl.net
Subject: Re: CCL:diffusion coefficient from mean square displacement
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Hannes Loeffler wrote:
I assume you are using periodic boundary conditions
for the bulk liquid. Make sure you are treating 
periodic boundary conditions correctly in the calculation
of the MSD. 


Richard Gillilan
MacCHESS Cornell

> 
> Hello,
> 
> I'm currently trying to obtain the diffusion coefficient from the mean square
> displacement (as a test case I simulated pure water). The diffusion coefficient
> may than be derived from the long time behavior of the MSD curve (slope).
> 
> But what does "long time" mean? I observe that the MSD curve becomes nearly
> linear after a few pico second but after some pico seconds later the line starts
> to rise again with an obviously larger slope.  Does this tell me anything about
> the quality of the potential used?  Should I be concerned about the "non-linear"
> MSD curve?
> 
> Hannes.
> 
> --
> Hannes Loeffler | tel: +43-(0)512-507-5166 | fax: +43-(0)512-507-2714
> http://www-c724.uibk.ac.at/staff/loeffler/ | mailto:Hannes.Loeffler {*at*} uibk.ac.at
> Institute for General, Inorganic and Theoretical Chemistry
> University of Innsbruck, Austria
> 
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