First-principles study of H adsorption on and absorption in Cu(1Â 1Â 1) surface

Periodic, self-consistent density functional theory calculations have been employed to investigate hydrogen adsorption on and absorption in Cu(1 1 1) surface. It turns out that subsurface site adsorption was not preferred below 1 ML coverage. This result does not support the observations reported by Lee and Plummer that subsurface site was preferred at high coverage (between 0.5 and 0.66 ML) [Surf. Sci. 498 (2002) 229]. The loss peak of 928 cm−1 assigned to absorbed H at a subsurface site in their work has been attributed to asymmetric stretching mode for surface threefold hollow site adsorption, resulting from a reduced symmetry of adsorbed hydrogen from our calculations.