Calculation of the self-consistent phonon spectrum of hcp He4

A numerical computation is carried out of the phonon spectrum of hcp He4 with the self-consistent phonon theory. Dispersion curves in symmetry directions are compared with recent measurements using the inelastic-neutron-scattering technique. The computed anisotropy of the sound velocity is also compared with recent experimental results on acoustic propagation in oriented single crystals. © 1968 The American Physical Society.