Monte Carlo study of linear chain submonolayer structures. Application to Li/W(1 1 2)

The lattice gas model for adsorption of alkaline elements on W(1 1 2) surface is studied by Monte Carlo simulations. The model includes dipole–dipole interaction as well as long-range indirect interaction. The numerical analysis of ground states shows that truncation of the indirect interaction even at 200 Å may change a phase diagram, i.e., new long-periodic phases might occur. The phase diagram for Li/W(1 1 2) is constructed and chain structures (9 × 1), (6 × 1), (4 × 1), (3 × 1), and (2 × 1) are found to be stable at low temperatures. It is shown that the (4 × 1) phase melts through incommensurate phase. Role of thermal fluctuation is discussed by comparison of Monte Carlo results with mean field calculations.