MOBILITY EDGES FOR THE QUANTUM PERCOLATION PROBLEM IN 2 AND 3 DIMENSIONS

Numerical results are reported for the quantum site-percolation problem. For the square lattice and the simple cubic lattice quantum percolation thresholds pq are calculated by studying the sensitivity of eigenvalues to a change in boundary conditions. Observing the energy dependence of the transition from localized to extended states, mobility edge trajectories are calculated. We obtain pq=0.45 in three dimensions and pq=0.70 in two dimensions. The latter value of pq is identified with a transition from weakly to strongly localized states, according to a similar localization behavior observed for the Anderson problem. © 1990 The American Physical Society.