Full quantification of frequency-dependent interfacial thermal conductance contributed by two- and three-phonon scattering processes from nonequilibrium molecular dynamics simulations

Understanding phonon transport across interfaces serves as a major tool to advance a diverse spectrum of fundamental and applied research. Unlike bulk materials, where the three-phonon scattering process is relatively straightforward to investigate, little research has been dedicated to the detailed analysis of the three-phonon scattering process at interfaces due to the complexity of interfaces and the mismatch of phonon dispersions of the two connecting parts. Based on the nonequilibrium molecular dynamics simulation, which is one of the most popular approaches to investigate the thermal conductance, we develop an explicit theoretical framework by considering the full third-order force constants field to quantify the two- and three-phonon scattering at interfaces. Bulk Ar is used as a benchmark to validate the computational scheme by comparing the results with those using the all-order phonon scattering method [frequency-dependent directly decomposed method; Y. Zhou and M. Hu, Phys. Rev. B 92, 195205 (2015)]. Then, Ar--heavy Ar and Si-Ge interfaces are studied and the respective role of two- and three-phonon scattering processes is quantitatively characterized at different temperatures. Moreover, all four different types of the three-phonon scattering process are explicitly evaluated. The method developed herein for splitting the two- and three-phonon scattering processes in the interfacial heat transport is expected to advance our understanding of the phonon process at interfaces, and will facilitate designing high-performance interfacial structures in terms of efficient thermal management.