Effects of structure on transport coefficients in a random medium

The transport coefficients for a system of classical particles moving in a random medium are shown to depend on the detailed structure of the medium even at strictly fixed scatterer concentration. An example is developed in which the diffusion coefficient can be expressed in terms of the distribution of distances between scatterers; this expression reduces considerably the maximum and average relative error when compared with previous results. Some statistical properties of the distribution of coefficients at fixed concentration are investigated