Full-spectrum phonon relaxation times in crystalline Si from molecular dynamics simulations

The lattice vibrations of a periodic silicon crystal are simulated by a molecular dynamics simulation. The history of atomic displacements and velocities obtained is used to compute the amplitudes of all phonon modes supported by the lattice. The phonon amplitude autocorrelation coefficients are found to decay exponentially in time, in agreement with single-mode relaxation time models for phonon scattering. However, the relaxation times extracted from the correlation curves are found to differ significantly from the empirical formulas currently used in models for microscale thermal transport, suggesting that improved relaxation time models are needed for accurate predictions in complex small-scale heat transfer systems.