[Pw_forum] Symmetry of IFCs (Harmonic) for Si

[Navaneetha Krishnan]

Hello QE users,

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?

Thanks a lot!
--Navaneeth
Caltech.
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