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<p>Dear Lorenzo and Pascal</p>
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<p>Thank you so much for your kind replies. </p>
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<p>Best Regards, </p>
<p>Nam Tran</p>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> pw_forum-bounces@pwscf.org <pw_forum-bounces@pwscf.org> on behalf of Lorenzo Paulatto <paulatz@gmail.com><br>
<b>Sent:</b> Monday, October 30, 2017 7:10:17 PM<br>
<b>To:</b> pw_forum@pwscf.org<br>
<b>Subject:</b> Re: [Pw_forum] How to calculate Mean Square Displacement (MSD)</font>
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<div class="PlainText">On 30/10/17 08:29, Nam Tran wrote:<br>
> I do not know whether I should consider the distance with atom that goes <br>
> about outside the box (a) or its image (b). Please check the image below <br>
<br>
Usually the right thing is to consider the smallest of all the possible <br>
distances. I.e. you put the red atom in all the positions which are <br>
equivalent by periodic boundary conditions, these in principle are <br>
infinite but going up to the second neighboring cell is usually more <br>
than enough; for each case you take the distance with the blue atom, and <br>
you take the minimum of all the distances.<br>
<br>
kind regards<br>
<br>
<br>
-- <br>
Lorenzo Paulatto - Paris<br>
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