Recent experiments performed at high gas partial pressures indicate that ruthenium can support unusually high concentrations of oxygen at the surface. To investigate the structure and stability of high coverage oxygen structures, we performed density functional theory calculations, within the generalized gradient approximation, for O adlayers on Ru(0001) from low coverage up to a full monolayer. We achieve quantitative agreement with previous low-energy electron diffraction intensity analyses for the (2×2) and (2×1) phases and predict that an O adlayer with a (1×1) periodicity and coverage Θ=1 can form on Ru(0001), where the O adatoms occupy hcp-hollow sites. © 1996 The American Physical Society.

• Received 22 January 1996

DOI:https://doi.org/10.1103/PhysRevB.54.2868