Lattice dynamics of hexagonal MoS2studied by neutron scattering

Phonon-dispersion curves for the hexagonal-layered compound Mo${\mathrm{S}}_2$ have been measured at room temperature by inelastic-neutron-scattering techniques for the [100] and [001] directions. The results have been analyzed on the basis of a model which includes valence forces between atoms in a layer and axially symmetric forces between atoms in neighboring layers. While the model reproduces the essential over-all features of the data, the present analysis indicates the need for a more sophisticated treatment of valence forces and/or for the inclusion of the atomic polarizabilities. The temperature dependence of the specific heat and the Debye temperature have been calculated from the model.