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Abstract:
Understanding heat transport in semiconductors and insulators is of fundamental significance, for instance, for renewable energy harvesting and conversion in thermoelectric devices. Lattice dynamics provides a powerful framework for the description of heat transport from the phonon scattering perspective and naturally includes quantum effects in the atomic vibrations. However, only the leading orders of anharmonicity are accounted for. In comparison, the Green-Kubo method is based on equilibrium Molecular dynamics simulations and the fluctuation-dissipation theorem is utilized to calculate the thermal conductivity for materials with strong anharmonicity. In this method, anharmonic effects are fully accounted for, but quantum-mechanical effects are not included in the nuclear dynamics. A comparison between these two methods is needed to understand under which circumstances which method is preferable. Most importantly, this sheds light on the validity range of the respective approximations, i.e., the perturbative treatment of anharmonicity and the classical treatment of the nuclear dynamics.
