[Pw_forum] About the mean square displacement in CP output

[Sandro Scandolo]

Dear Bernard,

if it converges to a finite value, your system is a solid (a crystal or 
a glass), not a fluid, so it makes no sense to compute the diffusion 
coefficient with MD, as the time scale for diffusion in solids are 
dictated by defect diffusion, which takes place on a much longer time 
scale than a MD simulation.

NB: The MSD is also printed out (together with the temperature of each 
species) in the standard output of cp.x, every iprint.

Regards
Sandro

On 30/04/2010 17:28, Bertrand SITAMTZE wrote:
> Dear Sandro,
>
> Thanks very much for giving tangible responses to my questions.
> My aim was to compute the diffusion coefficient using the linear 
> dependence of the MDS(t).  Now that it converge to a finite value, how 
> should I proceed?
>
> Your help is of great interest for me.
> Thanks once again
>
> ****************************
> Bertrand SITAMTZE YOUMBI
> Laboratory of Material Sciences
> Department of Physics
> University of Yaounde I-Cameroon
> ************************************
>
>
>
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-- 
Sandro Scandolo, ICTP | http://www.ictp.it/~scandolo

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