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Abstract

Molecular dynamics simulation method is used for calculating defects, such as monoatomic vacancies and nanovoids, influence on thermal conductivity of silicon at 500 K. Nonlinear reduction on thermal conductivity with the increase of defect volume fraction was found. Based on Hamilton equation of lattice vibration, phonon relaxation time can be extracted from system spectral energy density which has been calculated from 2D Fourier transformation of atomic trajectories. Compared with heat capacity and group velocity of each phonon, relaxation time was found to be the dominant factor for the nonlinear reduction on thermal conductivity of silicon. This method used here can be easily transferred for investigating other materials where thermal transport are governed by diffusive lattice vibration.