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Abstract:
The interrelation between the surface symmetry and diffusion of adsorbed atoms is studied theoretically on a model face-centred cubic (fcc) (111) surface within the lattice-gas approximation. Diffusion proceeds through two
non-equivalent sites on the fcc(111) surface. Short-range repulsive interaction between particles in the nearestneighbour non-equivalent sites is considered. This repulsion leads to a modification of the occupation numbers of
both kinds of site and to changes in the energy barrier height for diffusion. The chemical surface diffusion coefficient, D, has been found to be strongly dependent on coverage, θ, the
interaction strength between adatoms, and the difference between the activation energies, ∆E. In the case of a small
∆E value, the diffusion coefficient D increases with θ, as was expected for repulsive interaction. In our model the
increase of D at θ=0.5 is reduced for higher values of ∆E and a local maximum of D(θ) is observed.
