Fig. 4. Phonon renormalization and effect on thermal transport.

a Group velocities extracted from experiments and simulations (see “Methods” for details) for the TA_c along [100] (measured with CTAX at Q = (1.5, 0, 1) and (1.8,0,1)) and b LO_c along [001]. Open circles show Q corresponding to experimental measurements, solid lines are for v_g from experiments and dashed lines for v_g from simulations. c Measured κ (circles) and calculated κ_lat (lines and markers) along the a, b, and c crystallographic directions. Lines represent κ_lat computed with almaBTE and triangles are values from TDEP, while stars are from almaBTE, but with renormalized Φ⁽²⁾ from TDEP. d Norm of Φ⁽²⁾ from DFT (0 K) and TDEP (Pnma at 300, 600 K and Cmcm at 800 K). e Phonon linewidths calculated with Φ⁽²⁾ from 0 K DFT (T_BE  = 300, 600 and 846 K) and 600 K TDEP (T_BE = 846 K) with fixed Φ⁽³⁾ (almaBTE). f Cumulative κ_lat (T_BE = 300 K) from RTA with Φ⁽²⁾ from 0 K DFT (v_g,0K + τ_0K) and 600 K TDEP (v_g,600K + τ_600K), as well as mixed group velocities and lifetimes (v_g,600K + τ_0K, and v_g,0K + τ_600K).