Thermal conduction and interface effects in nanoscale Fermi-Pasta-Ulam conductors

TL;DR

This study uses molecular dynamics simulations to analyze heat transfer and interface effects in nanoscale FPU conductors, revealing how bulk reservoirs influence temperature profiles and interface behavior at different temperatures.

Contribution

It introduces a simulation approach that includes reservoirs in the model, providing new insights into interface effects and temperature profiles in nanoscale conductors.

Findings

Temperature profiles exhibit directional features at low temperatures.

Including reservoirs eliminates non-monotonous temperature variations.

Large reservoirs make temperature profiles independent of boundary thermalization details.

Abstract

We perform classical non-equilibrium molecular dynamics simulations to calculate heat flow through a microscopic junction connecting two larger reservoirs. In contrast to earlier works, we also include the reservoirs in the simulated region to study the effect of the bulk-nanostructure interfaces and the bulk conductance. The scalar Fermi--Pasta--Ulam (FPU) model is used to describe the effects of anharmonic interactions in a simple manner. The temperature profile close to the junction in the low temperature limit is shown to exhibit strong directional features that fade out when temperature increases. Simulating both the FPU chain and the two bulk regions is also shown to eliminate the non-monotous temperature variations found for simpler geometries and models. We show that with sufficiently large reservoirs, the temperature profile in the chain does not depend on the details of thermalization used at the boundaries.