Delocalization in disordered chains with random symmetrical impurities

We study in this paper, with the context of a tight-binding on-side model, the electronic properties of one-dimensional random lattices with correlate d impurities. We show that, when symmetrical impurities epsilon (b)epsilon (c)epsilon (b) are inserted in a host chain of site energy epsilon (a) and a constant hopping interaction V, diffusion will occur even when epsilon (c ) is random. We provide analytic expressions for the transmittance and conf irm the theoretical results by a great deal of numerical calculations. When epsilon (b) = V, we find that the mean-square displacement (MSD) follows t he law (m(2)) proportional to t(beta) with beta = 2.0 for epsilon (c) = con stant and beta = 1.0 for epsilon (c) = epsilon (r) = random, respectively.