Molecular Dynamics Simulation of Phonon Transport in EDIP Silicon

In this paper, molecular dynamics (MD) simulation is employed to compute thermal conductivity, dispersion curves and single mode relaxation times for bulk silicon. A newly-developed environment-dependent interatomic potential (EDIP) is used in our simulations. Using the Green-Kubo method, simulations of bulk silicon thermal conductivity are conducted using 216 to 4096 atoms. The effect of domain size is explored for different temperatures. Thermal conductivity predictions are found to converge to a bulk value for simulations containing 1000 atoms or more, even though the domain is much smaller than the phonon mean free path. A domain-size independent thermal conductivity is computed for temperatures ranging from 300 K to 1000 K and is shown to compare reasonably well with experimental data without the need for correction factors. The MD results are analyzed to obtain phonon dispersion curves along the [100] direction. Dispersion curves are also obtained using EDIP under a harmonic approximation and the classical dynamical matrix approach. The two sets of curves agree reasonably well. Furthermore, single mode phonon relaxation times are computed from the MD simulations. The trend can be curve-fit by third or fourth-order polynomials.