Eigendisplacement units

Dear all,

I want to make frozen phonon calculations using the eigendisplacements computed in DFPT calculations. I use anaddb in order to print the eigendisplacements and I managed to print the vectors for the qpts needed. The displacements vectors are printed in cartesian coordinates but I wondered in what units are they printed (bohrs, Angs, etc.)?

Also do I need to multiply by a given factor (inverse sqrt root of frequency)? And if so in what units should this prefactor be.

Thanks for your help

Hello Felix,

  1. check if the freezedispl anaddb variable does what you want (normalization may still be an issue)
  2. the displacements should be in bohr, but are just the eigenvectors multiplied by 1/sqrt(M) afaik. The real displacement operator in a second quantization sense needs the 1/sqrt(omega) as well, with the creation/annihilation operators:
    Formulations — Phonopy v.2.11.0
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