begin perfect
phonon_center_site 0.5 0.5 0
phonon_center_radius 1
end
begin vac1
phonon_center_site 0.5 0.5 0
phonon_center_radius 1
end
begin vac2
phonon_center_site 0.0 0.0 0
phonon_center_radius 1
end
begin vac1-vac2
phonon_center_site 0.25 0.25 0
phonon_center_radius 1
end
