Normal mode decomposition of atomic motion in solids

TL;DR

This paper discusses the decomposition of atomic motion into normal modes in solids, explaining classifications like phonons and diffusons, and demonstrating how this formalism predicts thermal properties such as heat capacity and thermal conductivity.

Contribution

It provides a comprehensive overview of normal mode decomposition in solids, including classifications and applications to thermal property predictions.

Findings

Normal mode decomposition effectively explains thermal properties.

Classification of modes includes phonons, propagons, diffusons, and locons.

Normal mode formalism can predict heat capacity and thermal conductivity.

Abstract

Decomposition of atomic motion into individual normal modes has led to remarkable success in microscopically understanding thermal properties and thermodynamics in simple solids. We start this chapter with an example of decomposing atomic motion of a simple monatomic linear chain crystal into normal modes followed by a more general, classical normal mode formalism. Different classifications of normal modes such as phonons, propagons, diffusons, and locons are introduced. Finally, heat capacity and thermal conductivity predictions from the normal mode formalism are demonstrated.