Edge states induce boundary temperature jump in molecular dynamics simulation of heat conduction

TL;DR

This paper reveals that edge-localized modes cause boundary temperature jumps in molecular dynamics heat conduction simulations, and proposes shifting heat baths away from edges to improve temperature profiles and thermal conductivity accuracy.

Contribution

It identifies the role of edge states in boundary temperature jumps and offers a practical solution to improve simulation accuracy.

Findings

Boundary temperature jump is caused by edge modes localized at system edges.

Shifting heat baths away from edges eliminates temperature jumps.

Improved temperature profiles lead to more accurate thermal conductivity calculations.

Abstract

We point out that the origin of the commonly occurred boundary temperature jump in the application of No\'se-Hoover heat bath in molecular dynamics is related to the edge modes, which are exponentially localized at the edge of the system. If heat baths are applied to these edge regions, the injected thermal energy will be localized thus leading to a boundary temperature jump. The jump can be eliminated by shifting the location of heat baths away from edge regions. Following this suggestion, a very good temperature profile is obtained without increasing any simulation time, and the accuracy of thermal conductivity calculated can be largely improved.