Indirect interaction in Ag and Pd adsorbed layers on the Mo(1 1 2) surface

The structures of Ag adsorbed layers on the Mo(1 1 2) surface have been studied by low energy electron diffraction (LEED) and compared with Pd structures on this surface. Performed DFT calculations have shown that the dominant interaction at low coverages both in Ag and Pd layers is an attraction of adjacent adatoms, which explains the formation of atomic rows lying in the substrate furrows. The sheets of Fermi surface of Mo(1 1 2) originated by surface bands provide the period of Friedel oscillations approximately equal to 2 lattice periods in the direction normal to the furrows, which leads to the appearance of the minimum of the potential of the indirect lateral interaction at this distance and, for Pd coverage θ = 0.5, results in the formation of the missing-row p(1 × 2) structure. The absence of the missing-row structure for the same coverage of Ag is caused by the incoherence of Ag chains with the substrate, which stems from the larger diameter of Ag adatoms.