Fig. 6: Green–Kubo lattice thermal conductivity.

a Difference in the calculated lattice thermal conductivity using the Green–Kubo method (Eq. (6)) and the Boltzmann transport equation. b Phonon lifetimes of GeTe (see text for explanation) in the Green–Kubo and Boltzmann transport equation approach plotted vs. TDEP frequency of phonon modes. Inset shows the region of soft phonon modes where the change is most noticeable.