Atomistic Visualization of Ballistic Phonon Transport

Heat transfer in solid materials at short time scales, short length scales, and low temperatures is governed by the transport of ballistic phonons. In anisotropic crystals, the energy carried by these phonons is strongly channeled into well-defined directions in a phenomenon known as phonon focusing. Presented here is a new molecular dynamics simulation approach for visualizing acoustic phonon focusing in anisotropic crystals. An advantage of this approach over experimental phonon imaging techniques is that it allows examination of phonon propagation at selected modes and frequencies. The spatial, mode, and frequency dependence of ballistic energy transport gained with this approach will be useful for understanding heat transfer issues in high frequency electronics and short time scale laser-material interactions.