Computation of the thermal conductivity using classical and quantum molecular dynamics based methods

TL;DR

This paper compares classical and quantum molecular dynamics methods for calculating thermal conductivity in solid argon, revealing that classical methods match experimental data at low temperatures due to error compensation.

Contribution

It highlights the differences between classical and quantum approaches in thermal conductivity calculations and questions the validity of quantum methods at low temperatures.

Findings

Classical MD agrees with experiments at low temperatures.

Quantum MD does not match experimental data at low temperatures.

Error compensation explains the agreement of classical MD.

Abstract

The thermal conductivity of a model for solid argon is investigated using nonequilibrium molecular dynamics methods, as well as the traditional Boltzmann transport equation approach with input from molecular dynamics calculations, both with classical and quantum thermostats. A surprising result is that, at low temperatures, only the classical molecular dynamics technique is in agreement with the experimental data. We argue that this agreement is due to a compensation of errors, and raise the issue of an appropriate method for calculating thermal conductivities at low (below Debye) temperatures.