Chemical surface diffusion analysis by the time evolution of density profiles. The Monte Carlo simulations

We present two methods of the Monte Carlo analysis of the chemical diffusio n processes on solid surfaces. First method is based on the analysis of the decay of sinusoidal adsorbate density perturbations; the second one uses t he Boltzmann-Matano procedure applied to the step-like density profile. The usefulness of both these methods is shown on extraction of the chemical di ffusion coefficient from the numerical results. We have applied our two met hods to various realizations of 2 D lattice gas systems, simulating diffusi on of adsorbate on surfaces of crystal having hexagonal symmetry of adsorpt ion sites. In particular we were interested in the dependence of the diffus ion process on strength and sign of the interactions of the jumping adatom at its activated state. We have compared systems with the same equilibrium properties (same ordered and disordered phase structure) and different inte raction-dependent barriers for attractive and repulsive forces. (C) 2001 El sevier Science Ltd. All rights reserved.