Exactly equivalent thermal conductivity in finite systems from equilibrium and nonequilibrium molecular dynamics simulations

TL;DR

This paper demonstrates an exact equivalence between equilibrium and nonequilibrium molecular dynamics methods in calculating thermal conductivity for finite systems, validated through simulations of monolayer silicene.

Contribution

It establishes that EMD and NEMD yield identical thermal conductivity values for the same domain length when NEMD uses periodic boundary conditions.

Findings

EMD and NEMD methods produce identical thermal conductivity results under specific conditions.

The equivalence holds for finite systems with periodic boundary conditions in NEMD.

Validation using monolayer silicene confirms the theoretical result.

Abstract

In a previous paper [Physical Review B \textbf{103}, 035417 (2021)], we showed that the equilibrium molecular dynamics (EMD) method can be used to compute the apparent thermal conductivity of finite systems. It has been shown that the apparent thermal conductivity from EMD for a system with domain length $2L$ is equal to that from nonequilibrium molecular dynamics (NEMD) for a system with domain length $L$. Taking monolayer silicence with an accurate machine learning potential as an example, here we show that the thermal conductivity values from EMD and NEMD agree for the same domain length if the NEMD is applied with periodic boundary conditions in the transport direction. Our results thus establish an exact equivalence between EMD and NEMD for thermal conductivity calculations.