Collective surface diffusion on triangular and square interacting lattice gases

Danani, A, Ferrando, R, Scalas, E and Torri, M (1998) Collective surface diffusion on triangular and square interacting lattice gases. Surface Science, 409 (1). pp. 117-129. ISSN 0039-6028

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The collective (or chemical) diffusion in interacting repulsive lattice gases is studied both in triangular and square symmetries. The effect of lateral interactions at the saddle point position is taken into account. The collective diffusion coefficient Dc is calculated within the generalized Darken equation (GDE). Under this approximation memory effects are neglected and Dc is expressed as the ratio of the average jump rate〈w〉and of the zero-wave-vector static structure factor S(0). Both quantities are calculated by the cluster variation method with clusters of seven (in the triangular lattice) and nine (in the square lattice) sites. It is shown that Dc has a very complicated behaviour in the regions of the phase diagrams where ordered phases are formed. This happens at coverages around θ=1/3 and 2/3 in the triangular lattice and around θ=1/2 in the square lattice. The lateral interactions at the saddle point have strong quantitative effects on Dc, but many qualitative features are preserved. In the square lattice case, our results are compared to those of Monte Carlo simulations by Uebing and Gomer, with excellent agreement. This shows that memory effects are not of great importance even at low temperatures.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Mathematics
Subjects: Q Science > QA Mathematics > QA0273 Probabilities. Mathematical statistics
Q Science > QC Physics > QC0170 Atomic physics. Constitution and properties of matter Including molecular physics, relativity, quantum theory, and solid state physics
Depositing User: Enrico Scalas
Date Deposited: 02 Oct 2014 13:26
Last Modified: 02 Oct 2014 13:26
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