[Pw_forum] How to calculate Mean Square Displacement (MSD)

[Marzari Nicola]

You need to be able to follow genuine diffusion - eg a liquid, a superionic, a fast interstitial...

If you fold, your msd will always tend to a constant (rather than eg a straight line with finite slope, as a function of time).

Nic

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On 30 Oct 2017, at 10:13, Lorenzo Paulatto <paulatz at gmail.com<mailto:paulatz at gmail.com>> wrote:


On 30/10/17 10:09, Marzari Nicola wrote:
?? For MSD you should not fold back.

Re-reading the question i think you are right. But I also think that it
should not matter, i.e. that each atom should always stay close to its
initial position. If it matters the displacements are too large, maybe
the timestep is too large if doing molecular dynamics?

cheers

--
Lorenzo Paulatto - Paris
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