MgB2 example. Supercell dimension is 3x3x2. Forces were calculated using VASP with 500 eV cutoff energy, 0.2 eV smearing, and k-point mesh of 18x18x18 for the unit cell.

% phonopy -f vasprun.xml-{001..002}
% phonopy -p band.conf

The band path is referred to Bohnen et al., PRL 86, 5771 (2001).
