First-principles pseudopotential plane-wave calculations based upon density functional theory and the generalized-gradient approximation were used to study the adsorption, dissociation, and diffusion of hydrogen on the α-U(001) surface. Weak molecular chemisorption was observed for H2 approaching with its molecular axis parallel to the surface. The optimization of the adsorption geometries on the threefold hollow sites yields final configurations with H2 molecules moving towards the top site at both coverages considered, 0.25 and 0.5 monolayers. A low dissociation barrier of 0.081eV was determined for H2 dissociated from the one-fold top site with the H atoms falling into the two adjacent threefold hollow sites. The analysis of the density of states along the dissociation paths showed that the hybridization of U 5f and H 1s states only occurred when the H2 molecule was dissociated.

Hydrogen Adsorption, Dissociation and Diffusion on the α-U(001) Surface. J.L.Nie, H.Y.Xiao, X.T.Zu, F.Gao: Journal of Physics - Condensed Matter, 2008, 20[44], 445001 (10pp)