Fig. 4: Phonon scattering.
a The Gr\(\ddot{u}\)neisen parameter γ of acoustic (violet) and optical (orange) phonon branches. b The decomposed 3ph scattering phase space W3ph into the splitting and combination processes. c The decomposed 4ph scattering phase space W4ph into the splitting, redistribution, and combination processes. d Decomposed 4ph scattering rates into the normal and Umklapp processes. The inset represents the ratios between Umklapp and normal processes.
