Thermal conductivity decomposition and analysis using molecular dynamics simulations. Part I. Lennard-Jones argon

Using molecular dynamics simulations and the Green–Kubo method, the thermal transport in the Lennard-Jones argon face centered cubic crystal is described by two time constants related to the decay of the heat current autocorrelation function. The first time scale is associated with short wavelength acoustic phonons that have mean free paths equal to one half of their wavelength. The associated thermal conductivity is independent of temperature, and has a value around 0.09 W/m K. The second time scale is longer, and corresponds to acoustic phonons with mean free paths longer than one half of their wavelength. The associated thermal conductivity is temperature dependent, and ranges from 3.92 W/m K at a temperature of 10 K to 0.08 W/m K at a temperature of 100 K. This decomposition allows for a comparison of the crystal phase results with those from corresponding amorphous and liquid phases.