THE NATURE OF ELECTRONIC STATES IN A DISORDERED CHAIN WITH LONG-RANGED HOPPING AMPLITUDES

In this work we investigate the nature of the electronic states in a o ne-dimensional tight-binding model with on-site energetic disorder and long-ranged hopping amplitudes. These are assumed to follow a power-l aw decay behavior with distance in the form h(r) proportional to 1/r(a lpha), with alpha>1. Direct numerical diagonalization, finite-size sca ling and a spectral statistics analysis show that as alpha-->1 the loc alization length exhibits an exponential growth as the upper band edge is approached. Strong finite-size corrections are present in this reg ime near the upper band edge with the one-electron states displaying a strong level repulsion even at large, although finite, chains. (C) 19 98 Elsevier Science B.V. All rights reserved.