Anharmonicity strongly enhancing thermal interface conductance: A new anharmonic atomistic Green's function formalism

The traditional atomistic Green's function (AGF) was formulated in the harmonic regime, preventing it from capturing the role of anharmonicity in interfacial thermal transport. Incorporating anharmonicity into AGF has long been desired but remains challenging. We developed a rigorous anharmonic AGF model to incorporate anharmonicity at interfaces in 3-D structures with first-principles force constants. Thermal conductance of silicon- and aluminum-based interfaces is significantly enhanced resulting from the new channels opened by inelastic scattering. This work represents a major step forward for AGF and highlights the importance of anharmonicity at the interface.