Tight-binding molecular-dynamics study of phonon anharmonic effects in silicon and diamond

The anharmonic effects on phonons in silicon and diamond have been studied by molecular-dynamics simulations using an empirical tight-binding Hamiltonian. One-phonon spectral intensities of the zone-center and zone-boundary (X) modes have been calculated through the Fourier transform of the velocity-velocity correlation functions. This scheme allows a quantitative and nonperturbative study of phonon frequency shift and phonon linewidth as a function of temperature. The results obtained are in good agreement with experimental data.