Numerical simulation techniques were used to reproduce the non-Arrhenius temperature dependence of the transport properties of amorphous materials; as modelled by hopping on a 2-dimensional square lattice. Although an Arrhenius temperature dependence was assumed for individual hopping steps (where the activation energy depended upon the barrier heights), the resultant logarithmic diffusivity versus reciprocal temperature plot exhibited a convex curvature.

G.Xu: Journal of Non-Crystalline Solids, 1994, 170[1], 68-72