Dear all,(adsbygoogle = window.adsbygoogle || []).push({});

I'm trying to compute the dynamical matrix of a crystal with a pair potential.

One way would be to use the second derivatives of the potential, and an other is to compute it numerically.

Well, in both cases, I get troubles where atom i equal atom j.

Is there something I haven't get yet?

I go through each atoms (i=1,N) and for each pairs I go through each coordinates (x,y,z). But in the analytical expressions of the derevatives there is always 1/r which diverge when r=0.

Numerically I face to the same problem ....

Any advices?

Thanks in advance,

Eric.

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# Dynamical matrix calculation

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