We have also evaluated hydrogen adsorption energies ranging from low to high surface coverage on each surface. We find that the (111) surface is the least attractive to adsorbed hydrogen, while the (110) surface is the most attractive. This suggests two mechanism for hydriding: equilibrium hydriding nucleated by the most attractive LB sites and non-equilibrium hydriding facilitated by barrierless dissociation and high driving forces for subsurface diffusion on the (111) surface.