Methodology for determining the electronic thermal conductivity of metals via direct non-equilibrium ab initio molecular dynamics

摘要

Many physical properties of metals can be understood in terms of the freeelectron model, as proven by the Wiedemann-Franz law. According to this model,electronic thermal conductivity ($\kappa_{el}$) can be inferred from theBoltzmann transport equation (BTE). However, the BTE does not perform well forsome complex metals, such as Cu. Moreover, the BTE cannot clearly describe theorigin of the thermal energy carried by electrons or how this energy istransported in metals. The charge distribution of conduction electrons inmetals is known to reflect the electrostatic potential (EP) of the ion cores.Based on this premise, we develop a new methodology for evaluating$\kappa_{el}$ by combining the free electron model and non-equilibrium abinitio molecular dynamics (NEAIMD) simulations. We demonstrate that the kineticenergy of thermally excited electrons originates from the energy of the spatialelectrostatic potential oscillation (EPO), which is induced by the thermalmotion of ion cores. This method directly predicts the $\kappa_{el}$ of puremetals with a high degree of accuracy.