Phonon Dispersion Relations of bcc U and Mo from MD Simulations

The bcc uranium–molybdenum solid solution is of interest for the fabrication of monolithic fuels to replace highly-enriched uranium dispersion fuels in research and test reactors. Knowledge of crystal lattice vibrations is an important step to understanding many properties of such materials. The phonon dispersion relations of bcc ?-U, Mo, and U–Mo alloys are thus of great importance. In this study, the phonon dispersion relations of bcc U and Mo were investigated by means of molecular dynamics simulations using EAM and ADP interatomic potentials found in the literature. We compare the ability of both potentials to predict the phonon dispersion relations of these materials. Their performance was assessed using available first-principles simulation data or neutron scattering data. Dispersion curves in the high-symmetry directions of the Brillouin zone are presented along with a comparative study of the dispersion relations obtained with the different potentials. The EAM potential is demonstrated to be unsuitable to describe the phonon dispersion relations of bcc uranium. The results obtained provide additional understanding of the limitations of the potentials, and can be used as a basis to study U–Mo alloys’ phonon properties.