Molecular dynamics prediction of phonon-mediated thermal conductivity of f.c.c. Cu

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

“…4 that the vibrational thermal conductivity of the liquid Cu model slightly decreases from 1.1 W/(mK) to 1 W/(mK) as the temperature increases from 1300 K to 1800 K. Meanwhile, the heat flux relaxation time s q retains a constant value of about 0.059 ps in the studied temperature range. We should also note that in the direct vicinity of the melting temperature the vibrational thermal conductivity of the liquid Cu model is about 30% lower than the vibrational thermal conductivity of the f.c.c Cu model for which it is about 1.6 W/(mK) at 1300 K [11]. In addition, it can be pointed out that fitting the temperature dependence of the vibrational thermal conductivity of the liquid Cu model to a function T Àn gives n % 0.3 (see Fig.…”

“…In the studied temperature range, the exponential decay is characterized by a constant value of the heat flux relaxation time of about 0.059 ps. The vibrational thermal conductivity of the liquid Cu model slightly decreases from 1.1 W/(mK) to 1 W/ (mK) as the temperature increases from 1300 K to 1800 K. In the direct vicinity of the melting temperature it is about 30% lower than the vibrational thermal conductivity of the f.c.c Cu model [11]. We have demonstrated that the approximation of the mean free path of the vibrational modes as one half of the Debye wavelength is quite reasonable one for the liquid Cu model.…”

“…2-4, the Cartesian components of the heat current vector in a system described using an EAM potential model can be represented as [11]:…”

“…Despite difficulties in obtaining precise quantitative results in such extremely fast experiments, estimated values of the solidification velocity, about 60-100 m/s at (0.6-0.8)T m , have demonstrated that the kinetic properties of the crystal-melt interface in pure metals at deep undercoolings can be effectively assessed by molecular dynamics (MD) simulations [8,9]. However, it is well known that, because of the absence of a freeelectron contribution, classical MD simulations of metals are expected to underestimate the magnitude of the thermal conductivity (or thermal diffusivity), which includes in this case only the vibrational contribution [9][10][11]. Therefore, because of the thermal gradients caused by generation or absorption of latent heat in a local region surrounding the solid-liquid interface, one has to be sure that the heat flow in the model system occurs on a time scale that is rapid enough relative to the attachment of liquid atoms to the growing crystal [10].…”

“…In this context, in our previous work [11] we calculated the vibrational thermal conductivity of f.c.c. Cu over a wide temperature range.…”