LOCALIZATION PROPERTIES OF GENERAL PSEUDORANDOM DIMER MODELS

We study localization of states and transmittance of a one-dimensional lattice with incommensurate rapidly varying pseudo-random potential, when site energies are dimerized. The chosen model potential, V = V0 c os(2pialphan(v)), alpha irrational, nu > 1 and dimerization, is a pecu liar generalization of the random-dimer binary model and allows carefu l control of the localization properties for varying degrees of disord er. We find that insertion of short-range order in the form of adjacen t site energy dimerization, causes, in general, a strong increase of t he localization lengths and the behaviour of the Lyapunov exponent as a function of the energy is similar to commensurate situations. In par ticular for nu > 2, the binary alloy situation is reproduced and we co nfirm the presence of extended states near the two-site energies.