Dynamical properties of lattice thermal conduction

Kaburaki, Hideo; Li, J.*; Yip, S.*; Kimizuka, Hajime*

Thermal conductivity of the Lennard-Jones (LJ) argon system has been derived by the equilibrium molecular dynamics method with the Green-Kubo formalism, and dynamical aspects of thermal conduction have been studied by analyzing the heat flux autocorrelation function, in contrast to the conventional Peierls phonon Boltzmann concept. At low temperatures the correlation function shows a characteristic two-stage decay, and we attribute a short-time relaxation to single-particle motions in a local environment and an extended relaxation to collective atomic motions. The short-time relaxation process is best characterized by calculating the two extreme cases, the liquid state and the harmonic system. We conclude that single particle diffusive motions are not very different from liquid to solid in the high temperature region and approaches to a random state in the low temperature and harmonic limit.