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

[Nam Tran]

Dear QE experts,


I am trying to evaluate MSD for my simulation.

My problem is that when an atom exits the simulation cell.

I do not know whether I should consider the distance with atom that goes about outside the box (a) or its image (b). Please check the image below (Blue is the original position t=0, red is the position at time t)


[cid:eb89eef8-985a-4e94-b8fb-1e770ba0adec]
Best Regards

Nam Tran
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