Modeling interfacial phonon transport with normal mode dynamics

TL;DR

This paper introduces a new formalism for interfacial phonon transport based on normal mode interactions, applicable to both crystalline and non-crystalline materials, advancing understanding beyond traditional particle or wave models.

Contribution

It develops a rigorous, general framework for interfacial phonon transport derived from interatomic interactions projected onto normal modes, applicable to disordered systems.

Findings

Mode interactions contribute to interface conductance

Framework applies to crystalline and amorphous materials

Provides a force-based perspective on phonon energy exchange

Abstract

Traditional theories of interfacial heat transfer by atomic vibrations, also known as phonons, do not explain how vibrational mode interactions contribute to interface conductance. Traditional methods also use the concept of phonons as particles or waves which propagate and transmit energy through interfaces; such methods are therefore inapplicable to realistic non-crystalline systems where phonons are not propagating. Here we introduce a more general formalism of interfacial phonon transport, rigorously derived from interatomic interactions projected onto the normal modes of the system, showing for the first time how interactions between vibrational modes contribute to thermal interface conductance. This new physical picture is based on the concept of forces and energy exchange between modes, regardless of their propagating or non-propagating character, thus providing a general formalism to describe phonon transport in all solids regardless of disorder.