Anharmonic phonon-phonon scattering modeling of three-dimensional atomistic transport: An efficient quantum treatment

International audienceWe propose an original method to quantum mechanically treat anharmonic interactions in the atomistic non-equilibrium Green’s function (NEGF) simulation of phonon transport. We demonstrate that the so-called lowest order approximation (LOA), implemented through a rescaling technique and analytically continued by means of the Pad´e approximants, can be used to accurately model a third-order anharmonicity. Although the paper focuses on a specific self-energy, the method is applicable to a very wide class of physical interactions. We apply this approach to the simulationof the anharmonic phonon transport in realistic Si and Ge nanowires with uniform or discontinuous cross-section. The effect of increasing the temperature above 300 K is also investigated. In all the considered cases, we were able to obtain a good agreement with the routinely adopted self-consistent Born approximation (SCBA), at a remarkably lower computational cost. In the more complicated case of temperatures much higher than the room temperature, we found that the first-order Richardson extrapolation applied to the sequence of the Pad´e approximants N-1/N results in a significant acceleration of the convergence