Emergent Temperature Dependence of Friction from Quantum Many-Body Theory

Friction is a nonequilibrium many-body dissipation process in which interfacial sliding excites collective lattice vibrations, with phonons representing the corresponding quantum excitations. Building on our previous phononic framework for friction-induced phenomena, including nonmonotonic velocity dependence, anisotropic friction, and the phononic Doppler effect, this work focuses on the microscopic origin of temperature-dependent friction. We develop a quantum many-body formulation based on nonequilibrium Green's functions and Feynman-diagram perturbation theory, in which frictional energy dissipation is resolved into harmonicity-induced phonon radiation and anharmonicity-induced phonon scattering through their corresponding self-energies. The theory reveals that phonon radiation dominates at cryogenic temperatures and produces finite friction even in the low-temperature limit. As temperature increases, anharmonic phonon scattering becomes progressively stronger and eventually overtakes radiation as the primary dissipation channel. At higher temperatures, scattering-enhanced damping suppresses the population of phonons excited by sliding, thereby reducing the total dissipated energy and producing a nonmonotonic friction-temperature relation. Molecular dynamics simulations of the friction system consisting of a silicon block sliding over another silicon substrate reproduce the predicted trend and confirm the simultaneous enhancement of phonon scattering and suppression of friction-excited phonons. By varying the anharmonic interaction strength, the framework further unifies the nearly constant, increasing, nonmonotonic, and decreasing temperature dependences reported for different materials. These results demonstrate that temperature-dependent friction emerges naturally from the competition among phonon radiation, phonon scattering, and the suppression of phonon excitation, establishing a quantum many-body route toward predictive modeling of frictional energy dissipation.