Coupled Oscillators and Dielectric Function

TL;DR

This paper justifies a generalized Lorentz-Dirac model for dielectric functions using coupled damped oscillators, explaining its success in modeling technologically important crystalline materials.

Contribution

It provides a theoretical basis for the Lorentz-Dirac dielectric model through the response of coupled oscillators, enhancing understanding of its applicability.

Findings

The generalized model can be derived from coupled oscillator response functions.

The model explains the success of Lorentz-Dirac in describing crystal dielectric properties.

Coupled oscillators provide a physical foundation for the dielectric function approximation.

Abstract

A generalized Sellmeier model, also referred to as the Lorentz-Dirac model, has been used for the description of the dielectric function of a number of technologically important materials in the literature. This model represents the frequency-dependent dielectric function as a sum over Green functions of classical damped harmonic oscillators, much in analogy with the functional form used for the dynamic polarizability of an atom, but with one important addition, namely, a complex-valued oscillator strength in the numerator. Here, we show that this generalized functional form can be justified based on the response function of coupled damped oscillators. The encountered analogies suggest an explanation for the generally observed success of the Lorentz--Dirac model in describing the dielectric function of crystals of consummate technological significance.