Effects of correlations and lattice gas restriction on the collective diffusion

The combined effects of correlations and lattice gas restriction on the col lective diffusion behavior of one-dimensional concentration profiles are st udied. Correlations are introduced as a persistent or anti-persistent movem ent in the individual random walk performed by the diffusing particles. The value of the diffusivity as a function of correlation is obtained for the continuous case through a new and simple analytical method. For the single occupancy (lattice gas) case, the collective diffusion coefficient is calcu lated by using the Boltzmann-Matano method. It is shown that the collective behavior of the system makes the concentration profiles not to scale, and the values of the diffusion coefficient become dependent on the type and am ount of correlation and on the local concentration when the single occupanc y restriction is present. (C) 2001 Elsevier Science B.V. All rights reserve d.