LEED and DFT investigation on the (2 × 2)-S overlayer on Co(0 0 0 1)

The geometric surface structure of a (2 × 2)-S layer formed by adsorption of hydrogen sulfide at 185 K on the Co(0 0 0 1) surface has been determined by low energy electron diffraction (LEED) experiments and density-functional theory (DFT) calculations. The favored atomic configuration consists of sulfur atoms residing at the fcc-hollow sites with S-Co distance of 2.2 ± 0.1 Å. Buckling in the first layer is negligible and the three nearest-neighbor Co atoms below the S atom are symmetrically moved by 0.05 ± 0.09 Å along the surface away from the S atom. The DFT calculations confirm the hollow-site adsorption and give further information on the electronic structure of the system.