Diffusion of Particles Adsorbed on a Reconstructive Surface
The influence of surface reconstruction on diffusion of particles, adsorbed on the surface, is investigated in the framework of symmetrical four-position model. The analytical expressions for the free energy and chemical and jump diffusion coefficients are obtained assuming the lateral interaction between the particles is negligibly small. The coverage dependencies of the tracer, jump and chemical diffusion coefficients are calculated using the expressions and MC simulations. The results demonstrate clearly a drastic change of the behavior of all diffusion coefficients on the reconstructed surface.
Adsorption-Induced Surface Reconstruction Processes:. the Influence on the Adsorption-Desorption Kinetics and the Mobility of Adsorbed Atoms
In this paper we study the influence of adsorption-induced surface reconstruction on both the adsorption–desorption kinetics and the surface diffusion of adsorbed particles. The reconstruction is regarded as an order–disorder phase transition, which is described in the framework of the lattice gas formalism by the two-position (2P) model. Adsorption is studied by kinetic Monte Carlo simulations while surface diffusion coefficients are evaluated by using the classical Monte Carlo modeling. Utilizing Monte Carlo simulations we characterize how the behavior of the chemical (D), the jump (DJ) and the tracer (D*) diffusion coefficients depend on the different ordered phases predicted by the model.
Adsorption-induced surface reconstruction: predictions of a simple model
Surface reconstruction can be a spontaneous or adsorbate-induced phenomenon. The effect of chemisorption is the extensive restructuring of the substrate to form a completely new surface structure. Such a phase transition can be explained qualitatively by employing statistical models like the lattice-gas model. In this work we analyze in detail the two-position model introduced by Myshlyavtsev and Zhdanov [A.V. Myshlyavtsev, V.P. Zhdanov, J. Chem. Phys. 92 (1990) 3909]. The model is a simplified latticegas version of the HW(001) system, which presents a c(2 × 2) ordered structure below the critical temperature Tc. The phase diagram of the real system is reproduced only at low coverage (θ < 0.4). The phase diagram is obtained by the mean-field approximation as well as by Monte Carlo simulations through finite-size scaling techniques. Different kinds of situations can be observed depending on the characteristics of the metal-metal (J), adsorbate-adsorbate (ϵ) and metal-adsorbate (λ) interactions.