  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.
