[Pw_forum] Regarding Kpoint and qpoint grids

[Kondaiah Samudrala]

Dear all,

I am performing phonon dispersion calculations for AB2 type Body centered
tertagonal structure with lattice parameters a= 4.315 and c =6.990. While
performing SCF calculations, I used 10 X10 X7 k grid and i got all forces
are <10-5 eV/atom. After that, I used 4X4X3 q grid for phonon dispersion,
my o/p says symmetry breaking, where as If i am using 4 X4 X 4 q-grid my
phonon dispersion shows imaginary frequencies at acoustic phonons.

Pls help me in choosing Kpoint and qpoint grids for any crystal
structures(except cubic).



with regards
S. Appalakondaiah
University of Hyderbad
Hyderbad
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