Monte Carlo simulations of the interface layer in Pb/Cu(110); a tight-binding-model calculation

Abstract

Monte Carlo simulations with energies computed via the tight-binding model are applied in studying the equilibrium properties of the interface layer in the system Pb/Cu(110). In a submonolayer range below 0.5 ML (ML monolayer), the model based on the coverage-dependent interactions reveals a lattice-gas random adsorption, an equilibrium adatom-substrate intermixing and formation of a centred c(2 × 2) phase. The process of intermixing is found to be coverage and temperature dependent. At high adatom concentration, 0.75-0.80 ML, as a result of very subtle competition between the strain energy and the energy gain due to mixing, the system forms a succession of commensurate unidimensional p(n × 1) structures. The results are in line with those recently obtained from scanning tunnelling microscopy and thermal energy atom scattering observations.

Computational study of stripe alloy formation on stepped surfaces

“…4,12,14 The detailed simulation analysis reveals the crucial role of competing atomic interactions which control the fine interface energy balance. In the high coverage range, 0.75Ͻ Ͻ 0.8 ML, the subtle interplay between the surface strain energy and the energy gain by mixing in the layer, generate a number of exotic 2D alloyed structures.…”

“…10,11 This semiempirical potential has been extensively applied in contemporary Monte Carlo atomistic simulations of transition metals and intermetallic alloys. [10][11][12]14 Its advantage relates to adequate reproducing of real physical properties of surfaces and interfaces including point defects, dislocations, vacancies, grain boundaries, etc. 10,11 In TB SMA approach the total cohesive energy for an atom i is expressed by…”

Surface diffusion of Pb clusters on Cu(111) influenced by size dependent cluster-substrate misfit: Monte Carlo tight binding simulation model

“…The system Pb/Cu(1 1 1) is of interest since in low coverage range, at Pb atom concentrations less than 37.5%, the adlayer exhibits important expansion, while at given critical coverage of 56.3%, compressed Pb islands are formed with reduced lattice constant by 2.65% with respect to the bulk Pb phase [20]. This effect strongly suggests dramatic change in the magnitude of lateral interactions from low to high coverage range which reflect the environment dependent character of interactions in a 2D layer [14][15][16].…”

“…It has been demonstrated in a number of studies that computer simulations based on tight binding second moment approximation of electron density of states (TB SMA) potentials reveal important features of monoatomic layers adsorbed on crystal surfaces and exactly follow the experimentally observed behavior [12][13][14][15][16]. In this study we have applied TB SMA potential between interacting atoms for center of mass diffusion of small 2D clusters on Cu(1 1 1) surface.…”

“…The diffusion coefficient D is evaluated by a linear fit of the 2D mean square displacement (MSD) of the cluster with specific size N. 1 · 10 6 MC attempts per atom have been performed to ensure that the diffusive regime is reached and thus, the MSD calculated from the cluster trajectory exhibits linear behavior. All simulation details are described elsewhere [14][15][16].…”