First-principles study on the adsorption and dissociation of H2 molecules on Be(0 0 0 1) surfaces

Abstract

The interactions of hydrogen molecules (H2) and Be(0001) surfaces have been studied by using density functional theory based first-principles calculations. The parallel and vertical configurations of H2 on the Be(0001) surface were considered and the results show that H2 adsorption on the Be(0001) surface is a weak physisorption and hydrogen atom (H) adsorption is a strong chemisorption. The critical dissociation distance of vertical H2 adsorption (∼0.6–0.8Å) is found to be shorter than that of parallel H2 adsorption (∼1.2–1.5Å) on perfect Be(0001) surface. Interestingly, the parallel H2 adsorption along the [112¯0] direction on perfect Be(0001) surface is found to be stable without dissociation. The dissociation barriers and the dissociated configurations of H2 depend on the initial H2 configurations and adsorption sites. In addition, our results show that vacancy defects on the Be(0001) surfaces have a notable effect on the interaction of H2 and the surface.