Nonequilibrium Green's function approach to mesoscopic thermal transport

TL;DR

This paper develops a nonequilibrium Green's function method to analyze thermal transport in nanojunctions, revealing the significant impact of nonlinear interactions on phonon transmission and thermal conductance.

Contribution

It introduces a first-principles approach for thermal current calculation in nonlinear nanojunction systems, emphasizing the role of nonlinearity and high-order phonon processes.

Findings

Nonlinearity affects thermal conductance even at low temperatures.

Nonlinear interactions suppress phonon transmission at room temperature.

Thermal conductance peaks around 400K, matching experimental data.

Abstract

We present a formulation of a nonequilibrium Green's function method for thermal current in nanojunction atomic systems with nonlinear interactions. This first-principle approach is applied to the calculation of the thermal conductance in carbon nanotube junctions. It is shown that nonlinearity already becomes important at low temperatures. Nonlinear interactions greatly suppress phonon transmission at room temperature. The peak of thermal conductance is found to be around 400K, in good agreement with experiments. High-order phonon scattering processes are important for diffusive heat transport.