QHA-LD with phonons from entire Brillouin zone

spiekermann

Dear Alessandro,
dear crystal-developers,

do I understand correctly that the QHA in crystal is based on gamma-point phonons only?

Thank you!
Kind regards,
Georg

aerba

Dear Georg,

It is correct. Note that of course if you build a supercell, band folding will bring back at Gamma phonons that would be formally assigned to other k points, which in the end allows for QHA calculations also with phonons out of Gamma.

For instance with something like:

SUPERCEL
2 0 0
0 2 0
0 0 2
QHA
END

you would be building a 2x2x2 supercell (relative to the primitive one), and performing a QHA on it (i.e. from harmonic frequencies computed on the supercell, and thus equivalent to phonons at 8 k points).

Hope this sheds some light on the matter,

spiekermann

Dear Alessandro,
thank you for this explanation!
Kind regards,
Georg