Energetics of holmium adsorption on Mo(1Â 1Â 2) surface

Adsorption and formation of ordered structures of Ho atoms on Mo(1 1 2) surface are studied by LEED, work function measurement and first-principle calculations. It is found that the most favorable energetically periodic structure is (3 × 2) structure at coverage of θ = 2/3, in which separation of Ho atoms is very close to metallic diameter of holmium. LEED measurements and the ground state analysis have revealed that structures (4 × 1) with θ = 3/4 and (5 × 1) with θ = 4/5 are also favorable. There are no ordered structures at low coverages although the long-range indirect interaction between adatoms is present.