The effect of the crystal field on hydrogen excitations in metals

Hydrogen when in a metal can be treated as a body in a potential well. This potential is nearly harmonic, but in any real material it will be distorted by a crystal field. This paper discusses a formalism which can be used to treat this problem. It is a degenerate perturbation theory calculation similar to that used to treat the splitting of the electronic levels of an atom due to a crystal field. All the matrix elements needed to calculate the crystal-field perturbation for the first two levels are tabulated, and expressions are derived to give the differential cross-section for inelastic neutron scattering from single crystal and polycrystal materials. (orig.)