Vibrational contribution to thermal transport in liquid cooper: Equilibrium molecular dynamics study

Abstract

The vibrational contribution to the thermal transport properties of liquid Cu is investigated in detail in the temperature range 1300–1800K. The calculations are performed in the framework of equilibrium molecular dynamics making use of the Green–Kubo formalism and one of the most reliable embedded-atom method potentials for Cu. It is found that the temporal decay of the heat current autocorrelation function of the liquid Cu model can be described by a single exponential function, which is characterized in the studied temperature range by a constant value of the heat flux relaxation time of about 0.059ps. The vibrational thermal conductivity of the liquid Cu model slightly decreases with temperature from about 1.1W/(mK) at 1300K to about 1W/(mK) at 1800K. Near the melting temperature it is about 30% lower than the vibrational thermal conductivity of the f.c.c Cu model. The calculated thermal diffusivity of the liquid Cu model is demonstrated to retain a constant value of about 2.7×10−7m2/s in the studied temperature range, which is about two orders of magnitude higher than the atomic diffusivity in the model at the melting temperature. The vibrational contribution to the total thermal conductivity of liquid Cu is found to slightly decrease with temperature, being estimated as about 0.7–0.5% in the temperature range of 1400–1800K. Furthermore, the applicability of some simple theoretical treatments of vibrational thermal transport in liquid Cu is discussed.