Effect of van der Waals interaction on thermal expansion and thermal conductivity of graphite predicted from density-functional theory

Abstract

Graphite is a typical layered material, exhibiting many exceptional thermal properties, such as large ratio of thermal conductivity anisotropy and orientation dependent thermal expansion. These features are largely attributed to the weak interlayer van der Waals interaction and strong intralayer covalent bonds. To accurately predict the thermal properties of graphite and other layered materials, it is essential to correctly describe the interlayer van der Waals interaction. Here, we evaluate the performance of different treatments of van der Waals interaction in first-principles calculations by examining the thermal expansion behavior and thermal conductivity of graphite. We show that non-local van der Waals density functional is essential to correctly predict the thermal expansion coefficients and phonon dispersion, while the local-density approximation substantially overestimates the interlayer anharmonicity. Furthermore, the correlation between basal-plane thermal expansion and through-plane thermal conductivity is uncovered, which originates from the anharmonicity of interlayer bonds. The data presented here could serve as a benchmark for van der Waals density functionals in first-principles calculations and this work paves the road to fully understand the thermal transport in van der Waals materials with highly anisotropic vibrational properties.