The coherent potential approximation is a realizable effective medium scheme

Effective-medium approximation for composite media: Realizable single-scale dispersions

It is known that the popular effective medium approximation ~EMA! for the effective conductivity se of a composite is exactly realizable by certain multiscale hierarchical microstructures. We have found a class of periodic, single-scale dispersions that achieve the EMA function at a given phase conductivity ratio for a two-phase, two-dimensional composite over all volume fractions. Moreover, to...

Coherent potential approximation as a voltage probe

Investigation of the nonlocal coherent-potential approximation

Recently the nonlocal coherent-potential approximation (NLCPA) has been introduced by Jarrell and Krishnamurthy for describing the electronic structure of substitutionally-disordered systems. The NLCPA provides systematic corrections to the widely used coherent-potential approximation (CPA) whilst preserving the full symmetry of the underlying lattice. Here an analytical and systematic numerica...

Effective-Medium Approximation for Energy-Dependent Hopping on a Lattice

We have generalised the standard lattice Coherent-Potential-Approximation (CPA)/EffectiveMedium-Approximation (EMA) scheme to include the case of energy dependent hopping. This case is complicated by the fact that, due to the detailed-balance condition, the hopping rates wij are non-symmetric, i. e. wij 6ˆ wji. Results for the frequency dependent diffusion coefficient are compared with Monte-Ca...

Direct demonstration of the concept of unrestricted effective-medium approximation.

The modified unrestricted effective-medium refractive index is defined as one that yields accurate values of a representative set of far-field scattering characteristics (including the scattering matrix) for an object made of randomly heterogeneous materials. We validate the concept of the modified unrestricted effective-medium refractive index by comparing numerically exact superposition T-mat...