The Local Field and What It Means

Abstract

The easy link between the dielectric constant of isotropic media and the molecular polarizability of the constituents, is traditionally given by the Lorentz-Lorenz (LL) relation. The local field concept however upon which this relation is based, needs to be re-examined for highly inhomogeneous systems, like surfaces and interfaces. Local fields belong inherently to discrete dipole models, but for the comparison with continuum approaches only descriptions based on average fields, are the more suited ones. This holds particularly for the comparison with the Fourier-type solution of the continuum problem, upon which the classical Adler and Wiser papers [1, 2] are based.

Reflection anisotropy spectroscopy

“…Results are not yet available for metals. The relationship between the original formulation of the concept of local fields [116,117] and discrete dipole models has been clarified recently by Wijers and de Boeji [127][128][129][130]. (110): effects of surface morphology.…”

Polarizable dipole models for reflectance anisotropy spectroscopy: a review

“…On one hand, microscopic formulations seem to indicate that the K = 0 contributions to the surface optical response are minimal [16,72]; on the other hand, the PDM local field is readily responsible for the surface optical anisotropy of the examples presented in this paper. The bridging of these two different definitions of the local field is still an important open question whose answer will benefit surface optics [73], however this topic is beyond the scope of the article.…”