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

Adsorption and formation of ordered structures of Ho atoms on Mo(112) surface are studied by LEED, work function measurement and first-principle calculations. It is found that the most favorable energetically periodic structure is (32) structure at coverage of [thetas] =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 (41) with [thetas] =3/4 and (51) with [thetas] =4/5 are also favorable. There are no ordered structures at low coverages although the long-range indirect interaction between adatoms is present.