Monte Carlo Simulations of Metal Monoatomic Layers

摘要

The equilibrium properties and 2D phase transitions in metal mono-atomic layers adsorbed on crystal surfaces are discussed in the framework of 3D continuum space tight binding (TB) second moment approximation (SMA) model. The atomistic Monte Carlo simulations based on "realistic" many body potentials exactly reproduce the experimentally observed lattice gas behavior, surface alloying, formation of commensurate c(2 x 2) and quasi-unidimensional p(n x 1) phases, Ising type order disorder transition, influence of surface imperfections on the critical behavior. It is demonstrated that depending on the local atomic environment, symmetry and anisotropy of (111) and (110) fcc surfaces a coverage or configu-rational dependent interactions should be applied in the system. Since crucial to the success of simulations is the interatomic potential, it is argued that appropriate modification of the bulk value of the hopping integral £ in a band energy term leads to system behavior in fairly good agreement with the experimental findings.