Theoretical study of the interaction of hydrogen with metals

Abstract

Electronic structure calculations are carried out for simple metal hydrides and hydrogen adsorption on simple metal surfaces. The studies are based on the ab initio pseudopotential method and the local-density approximation. Structural and electronic properties of magnesium hydride are studied. The calculated structural properties include equilibrium lattice parameters, cohesive energy, elastic constants, bulk modulus, and phonon frequency. The electronic band structure, density of states, charge density distribution are also obtained. Superconductivity in doped magnesium hydride is proposed. Lithium beryllium hydride is studied because of its proposed metallic behavior. The relative stability of two perovskite structures" of lithium beryllium hydride is investigated. Band structures are calculated under ambient and high pressure conditions to determine whether the structures are metallic, The adsorption of hydrogen on the close-packed surface of Be and Mg are studied. The equilibrium distance between hydrogen and the surfaces, the adsorption energy, and the hydrogen oscillation frequency are calculated for hydrogen in the high-symmetry adsorption sites. The energetics for hydrogen to go into a subsurface site is also investigated. Charge density distribution, work function and potential are studied for the clean and hydrogen-covered surfaces. Electronic band structure and H-induced surface states are determined for hydrogen adsorption on Be. Surface energy of the clean surfaces is also calculated.