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<div class="moz-cite-prefix">the IFC should be symmetric w.r.t.
exchange of the two atoms and displacement directions as a
consequence of being second order derivatives. other symmetries
may apply in specific cases.<br>
difficult to comment more without more info on what you are
looking for.<br>
stefano<br>
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On 11/10/2014 09:16 AM, Navaneetha Krishnan wrote:<br>
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<div>Hello QE users,<br>
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I was investigating the IFCs generated by q2r.x after scf and
ph calculations. It looks like the force constant matrix for
certain pairs of atoms is not symmetric (with respect to the
cartesian coordinates). For silicon, the IFC matrices have to
be symmetric with respect to the cartesian coordinates -
right? For aluminum, the output is symmetric, as expected. Any
thoughts?<br>
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<div>Thanks a lot!<br>
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<div>--Navaneeth
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<div>Caltech.</div>
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