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