Mode-dependent phonon transport analysis of silicon crystal by molecular dynamics method

Abstract

In this work, we have investigated phonon transport in silicon crystal using molecular dynamics and lattice dynamics methods. The phonon relaxation time is derived from molecular phase space trajectories through two different analysis methods using normal mode projection and spectral energy density. By performing the calculations for wavevectors spanning the entire first Brillouin zone, we find that these two relaxation-time calculation methods give almost the same results despite the fundamental difference in the underlying theories. With the obtained phonon relaxation time and group velocity calculated by lattice dynamics method, we have quantified the contribution from each phonon mode to the overall thermal conductivity. In addition, by calculating the cumulative thermal conductivity, we have quantified contributions to thermal conductivity from phonons with different mean free paths to gain insight into the scale effect of heat conduction in nanoscale. © 2012 The Japan Society of Mechanical Engineers.