Abnormal Phonon Spectrum in EPW Including Quadrupole Polarization

[guodonglin]

I am currently using the EPW code to calculate electron-phonon coupling and transport properties for a 3D material. I encountered an issue regarding the phonon spectrum output when including quadrupole polarization effects.

Here are the details of the problem:

When I perform calculations without quadrupole polarization, the phonon spectrum is physically reasonable and matches expectations.

However, when I enable quadrupole polarization, the resulting phonon spectrum appears unphysical .


Could you kindly provide guidance on the following?

[stiwari]

Hi,

Can you kindly provide more information (including all input and output (.out) files) to debug the issue you are facing.

Best regards,
Sabya.

[guodonglin]

for quadrupole and none quadrupole, the input file is the same, namely, epw1.in. the output files are epw1.out and epw1.out-quad.

[Nina Girotto]

Hello,

Comparing your output files, you can notice the wannierization produced different results in the two calculations. Is it possible to provide initial projections explicitly, instead of using the 'random' option?

Best,

Nina.

[sponce]

Hello,

I confirm that this is the issue. Your Wannierization is of bad quality and different in the two outputs because you use random Wannier functions.

The use of 'random' is strongly discouraged as it often produce bad results.

Best wishes,
Samuel