A First-Principles Study of Hydrogen Diffusivity and Dissociation on δ-Pu (100) and (111) Surfaces

Abstract

The diffusivity and chemical reactivity of hydrogen on the δ-Pu (100) and (111) surfaces has been studied with density functional theory using both spin-polarization and spin–orbit coupling calculations. Comparison of the total electronic density of states and atomic hydrogen diffusion energies indicates that spin-polarization yields accurate results, with spin–orbit coupling yielding slightly smaller barriers to hopping between adsorption sites. On the (100) surface, both sets of calculations indicate that the dissociation reaction for molecular hydrogen is highly active at ambient conditions and results in the hydrogen ions bonded within the Pu surface, similar to hydride formation. In contrast, calculations on the (111) surface indicate a lower barrier for dissociation without the formation of the hydride-like end product. Our results help quantify the effect of spin–orbit coupling on hydrogen surface chemistry on δ-Pu. In addition, we observe that the degree of resulting corrosion could depend on the ...