Lattice dynamics of MnO

Phonon dispersion relationships have been determined for the acoustic branches in MnO along the [100], [011] and [111] directions by neutron spectrometry. The measurements have been interpreted in terms of the rigid-ion and the shell model. The rigid-ion model does not fit the data adequately and the shell model, while producing a much better fit to the data, cannot be said to give a satisfactory description.