The Role of Submonolayer Film Structure in the Surface Diffusion on Atomic Anisotropic Crystal Face: a Computer Experiment

We investigated the role of co-operative and structural effects in surface diffusion of adsorbed atoms with repulsive lateral interactions on the atomic anisotropic metal faces by computer simulation method. Such systems were been considered for which chain superstructures can be formed in submonolayer adsorbed films. It is shown that the diffusion coefficients D decrease rapidly with increasing coverage and island sizes in those concentration ranges where first order phase transitions take place. The dependence of D on concentration θ is pronounced very weakly in disordered films at temperatures above the critical one. Due to a crowdion mechanism, the diffusion coefficients are rising as the coverage increases in a homogeneous film in the presence of chain superstructure. Chains commence to change often their positions in the range of critical temperatures. In such conditions, crowdion (quasi-point) configurations of adatoms can associate into soliton-like (quasi-line) formations. The simulation results are compared with experimental data.