Dynamics of Phononic Dissipation at the Atomic Scale: Dependence on Internal Degrees of Freedom

TL;DR

This paper investigates how energy dissipates from a nano-particle to a substrate at the atomic level, revealing how different couplings and substrate properties influence phonon decay rates, with implications for friction and lubrication.

Contribution

It introduces a theoretical analysis of phonon dissipation dynamics considering various coupling types and substrate models, extending to realistic molecular and surface systems.

Findings

Decay rate of nano-particle phonons scales with the square of the interaction constant.

Different substrate dimensionalities and densities of states affect dissipation dynamics.

The analysis can be applied to realistic lubricants and complex substrates.

Abstract

Dynamics of dissipation of a local phonon distribution to the substrate is a key issue in friction between sliding surfaces as well as in boundary lubrication. We consider a model system consisting of an excited nano-particle which is weakly coupled with a substrate. Using three different methods we solve the dynamics of energy dissipation for different types of coupling between the nano-particle and the substrate, where different types of dimensionality and phonon densities of states were also considered for the substrate. In this paper, we present our analysis of transient properties of energy dissipation via phonon discharge in the microscopic level towards the substrate. Our theoretical analysis can be extended to treat realistic lubricant molecules or asperities, and also substrates with more complex densities of states. We found that the decay rate of the nano-particle phonons increases as the square of the interaction constant in the harmonic approximation.