Crystal Dynamics of Magnesium Oxide

The crystal dynamics of magnesium oxide have been studied by incorporating the effect of three-body interactions in the framework of the shell model on the lines of the work of Singh and Verma [Phys. Rev. B 2, 4288 (1970)]. The theoretical dispersion curves in the three symmetry directions and specific-heat variation with temperature have been calculated and compared with the corresponding experimental results. The experimentally observed second-order infrared absorption and the Raman spectra have also been interpreted by using the critical-point analysis and the combined-density-of-states approach. An excellent agreement has been obtained with the recently measured neutron-scattering, specific-heat, and second-order infrared-absorption and Raman-scattering data.