The influence of both pair-wise and 3-particle interactions upon the mobility of adsorbed particles diffusing on a lattice with triangular symmetry was studied. Two different techniques were used to describe the surface diffusion phenomenon. On one hand, explicit expressions for the chemical and jump diffusion coefficients were calculated by using a real-space renormalization group approach. A number of the real-space renormalization group transformations with blocks of different sizes and symmetries were investigated. In particular, it was shown that the precision of the method depended strongly not only on the number of sites in the real-space renormalization group blocks but also on their composition and structure. On the other hand, numerical simulations by using the Monte Carlo scheme was used to simulate the process of particle migration. Using both methods, adsorption isotherms for different temperatures and the coverage dependencies for the thermodynamic factor and the chemical diffusion coefficient were calculated. The behavior of the above mentioned quantities was compared when the adparticles interact via only either pair-wise or three-particle interactions. Despite the fact that both methods constituted very different approaches, the correspondence of numerical data with analytical results was surprisingly good. Therefore, it could be concluded that the real-space renormalization group method could be successfully applied for lattice gas systems to characterize the thermodynamic and kinetic properties of strongly interacting adsorbates.

Diffusion of Particles Adsorbed on a Triangular Lattice - Pairwise and Three-Particle Interactions. A.A.Tarasenko, F.Nieto, L.Jastrabík, C.Uebing: Surface Science, 2003, 536[1-3], 1-14