Molecular dynamics of a dilute solution of hydrogen in palladium

Abstract
Molecular-dynamics results on a dilute solution of H in Pd are presented and compared with available incoherent inelastic neutron-scattering results. The embedded-atom model adopted here does a good job of describing the H-Pd atomic forces probed by incoherent inelastic neutron scattering. The time correlation functions associated with the computed spectra are strongly damped and indicative of the anharmonicity that has been suggested as the principal contribution to the anomalous isotope dependence of the superconducting transition temperature in PdH. These results highlight the fact that the H-atom vibrations in Pd-H solutions are low-frequency, large-amplitude vibrations relative to vibrations of H atoms in usual covalent interactions. The rms displacement of the H atom from its mean position in the center of the Pd octahedron compares favorably with the available neutron-diffraction results.