Regular dynamics associated with heat transfer at the interface of model diamond {111} nanosurfaces

Nonequilibrium molecular dynamics simulations were performed to study the dynamics of heat transfer across the interface of two H-terminated diamond {111} nanosurfaces. It was found that when the surfaces are brought into contact, a coherent low-frequency oscillatory motion, normal to the interface, is initiated for the atomic layers of each surface. This motion lasts more than 50 ps, significantly longer than the relaxation of the interfacial force which occurs on a subpicosecond time scale. Amplitudes of these coherent oscillations gradually increase from the outer atomic layers to the interfacial layer. The temperature of the hot surface does not have a significant effect on the nature of oscillations. Thicker nanosurfaces have oscillations of lower frequency. This coherent oscillation of the surfaces' atomic layers creates beats in the potential energy of the surface and, thus, in the total energy content of the surface. The amplitude of the energy beat increases as the distance between the interfacial H-atom layers decreases. Thus, the atomic-level energy transfer dynamics from the hot surface to the cold surface is more complex than the exponential dynamics observed for overall heat transfer between the surfaces.