[QE-users] Fourier Interpolation of Phonon Bandstructure

[Ankit Sharma]

Hi,
I ran a gamma point phonon calculation for alpha-Ga2O3 and upon imposing
crystal asr I get pure translations with zero frequencies for the acoustic
modes, but when I run the phonon calculation on a grid (6x6x6) and
interpolate it using q2r.x and matdyn.x in specific IBZ directions, I get
negative frequencies at the Gamma point. I have used the same asr for
matdyn too.
I wanted to know, what might be going wrong with the interpolation or is
there a problem with convergence in the q point grid? The magnitude of
negative frequencies at the gamma point is less then 2THz.

Any help in this regard would be appreciated.

Thank You,
Ankit Sharma
University at Buffalo
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