A model, for the hopping of tagged particles on a lattice where a finite concentration of background particles gave rise to blocking (due to forbidden multiple site-occupancy), was extended to a situation where disorder existed on the lattice. The case of variable-bond hopping-rates was considered here in the strongly disordered limit where a finite concentration of the bonds was completely blocked. The self-diffusion coefficient was then of the form, (1-c)(1-p/pc)Dof; where pc was the percolation limit and f was a dynamic correlation factor. It was expected that f would be affected by the disorder, and this was estimated by using random-walk theory to calculate <cos θ>; where θ was the angle between successive jumps of a particle and a vacancy. Comprehensive simulations of tracer diffusion in a 2-dimensional square lattice were also performed for 0 < c < 1 and 0 < p < pc. The results were in good agreement with analytical results for small concentrations. The present approximate theory furnished a good description over the entire range; provided that a corrected form of <cos θ> was used.

Tracer Diffusion in Bond-Disordered Square Lattices L.F.Perondi, R.J.Elliott, K.Kaski: Journal of Physics - Condensed Matter, 1997, 9[38], 7933-48