Absorption in dipole-lattice models of dielectrics

TL;DR

This paper presents a classical microscopic model of dielectrics with nonlinear dipole-lattice interactions that naturally explains broadband absorption and includes spatial dispersion effects.

Contribution

It introduces a novel dipole-lattice model that accounts for broadband absorption without damping and calculates the permittivity's wavevector dependence.

Findings

Broadband absorption arises from lattice vibrations acting as a pseudo-reservoir.

Effective permittivity matches forms observed in real dielectrics.

Spatial dispersion is inherently included in the model.

Abstract

We develop a classical microscopic model of a dielectric. The model features nonlinear interaction terms between polarizable dipoles and lattice vibrations. The lattice vibrations are found to act as a pseudo-reservoir, giving broadband absorption of electromagnetic radiation without the addition of damping terms in the dynamics. The effective permittivity is calculated using a perturbative iteration method and is found to have the form associated with real dielectrics. Spatial dispersion is naturally included in the model and we also calculate the wavevector dependence of the permittivity.