On wave propagation in inhomogeneous systems

We present a theory of electron, electromagnetic, and elastic wave propagation in systems consisting of nonoverlapping scatterers in a host medium. The theory provides a framework for a unified description of wave propagation in three-dimensional periodic structures, finite slabs of layered structures, and systems with impurities: isolated impurities. impurity aggregates, or randomly distributed impurities. We point out the similarities and differences between the different cases considered, and discuss the numerical implementation of the formalism. (C) 2001 Elsevier Science B.V. All rights reserved.