Diffusion on simple heterogenous surfaces

Abstract

In this work we use the well‐known bivariate trap model with random topography in order to study the effects of surface heterogeneities on surface diffusion. Utilizing Monte Carlo simulations we characterize how the tracer, jump and chemical diffusion coefficients depend on temperature and concentration of deep traps, θ. In order to calculate the chemical diffusion coefficient we apply the fluctuation and the Kubo‐Green methods. Both methods are in good agreement at large values of θ only. The discrepancies are discussed and explained. The effects of heterogeneities are largely pronounced at low total coverage and low temperatures, where most of the adatoms are trapped by the deep traps. At high coverages the mobility of adatoms adsorbed on shallow traps dominate the diffusion behavior.

Adsorption of interacting monomers on spanning clusters of polyatomic species

“…Here, we have used both methodologies with the same accuracy. The thermodynamic factor entering the expression for the chemical diffusion coefficient [31][32][33][34] can be directly obtained from Fig. 3.…”

Percolation on patchwise heterogeneous surfaces under equilibrium conditions

“…One of the aspects requiring a better understanding is the way in which the energetic topography affects different adsorption processes. In fact, even though it has been shown that many molecular surface processes are indeed dependent on the way adsorptive energy is spatially distributed on the surface (topography) [20][21][22], a systematic study showing how the main characteristics determining the topography act on the percolation of adsorbed particles at equilibrium is far to be exhausted. The present work intends to be a new step in this direction.…”