Dielectric-constant evaluation from microstructures

We present an accurate, efficient algorithm for calculating the effective dielectric constant «̄ of periodic two-component composites with arbitrary unit-cell microstructures. The algorithm is based on a formulation of the relevant equations in the Bergman-Milton representation of «̄ that enables the use of the fast Fourier transform in their solution, coupled with the sum rules of the geometric spectral function. Our approach accurately reproduces known results, such as the two-dimensional checkerboard problem, and yields excellent agreement with experimentally measured results on random configurations of metallic spheres.