Phonon Thermal Transport in Diamond and Lonsdaleite: A Comparative Study of Empirical Potentials

The stacking sequence significantly affects the thermal conductivity of diamond. However, the inaccuracy of some widely used empirical potentials to calculate the anharmonic phonon transport in diamond, hinders the use of molecular dynamics simulations from revealing the detailed mechanism of phonon transport in diamond and other related materials with different stacking sequences. In this paper, a comparative study of four common carbon empirical potentials - Tersoff, Airebo, 2nd-rebo, and COMPASS - is performed to simulate the phonon thermal transport of diamond and lonsdaleite. The results show that the Tersoff potential, together with Airebo and 2nd-rebo potentials, is not suitable for describing the phonon transport mechanism in different diamond polytypes, both for harmonic phonon dispersion and anharmonic phonon scattering caused by stacking disorders. COMPASS potential gives a good fit for the acoustic phonon branches in all directions of diamond and accurately describes the band gaps between acoustic and optical branches, and is capable of representing the lattice dynamics and phonon thermal transport in diamond and lonsdaleite. The COMPASS potential is suitable for simulating the phonon thermal transport properties in diamond and lonsdaleite, and thus it is suitable for simulating the stacking disorder effect on the phonon thermal transport in diamond.