Localization phase diagram for the energetically and substitutionally disordered Anderson/quantum percolation model

Abstract

To study the localization of Frenkel excitons in binary systems, we consider a model that has features both of the Anderson model (diagonal disorder characterized by a probability distribution of width w) and of the quantum percolation model (substitutional disorder characterized by an occupational probability p for one of the components). With a finite-size scaling (phenomenological renormalization group) technique, and the concept of quantum connectivity, we calculate the position of the phase boundary separating localized from extended states in the w–p disorder plane. At the two endpoints of the boundary, we find that for the Anderson model the critical disorder is wc=15.95±0.25, and for the quantum percolation model the localization threshold is pq=0.477±0.011.