Bulk response of composites from finite samples

Abstract

The bulk macroscopic dielectric response of a disordered composite is calculated employing a large finite sample instead of an infinite one obtained by replicating a unit cell, as has usually been done. We explicitly account for boundary effects through the macroscopic depolarization field, and finite size corrections are minimized by the large size of the system. The generation of the composite and the calculation of the interactions between the great number of particles become feasible using a newly developed hierarchical multi-resolution scheme. The dielectric response of a composite made up of Ag spheres embedded in glass and the composition independent spectral density agree with those from previous simulations and we discuss their differences with analytical theories based on a renormalized polarizability. Confinement effects due to inhomogeneities close to the boundary of the system are also investigated. (C) 2003 Elsevier B.V. All rights reserved.