Phonon Thermal Transport in UO2 via Self-Consistent Perturbation Theory

Computing thermal transport from first-principles in UO2 is complicated due to the challenges associated with Mott physics. Here, we use irreducible derivative approaches to compute the cubic and quartic phonon interactions in UO2 from first principles, and we perform enhanced thermal transport computations by evaluating the phonon Green’s function via self-consistent diagrammatic perturbation theory. Our predicted phonon lifetimes at T = 600 K agree well with our inelastic neutron scattering measurements across the entire Brillouin zone, and our thermal conductivity predictions agree well with previous measurements. Finally, both the changes due to thermal expansion and self-consistent contributions are nontrivial at high temperatures, though the effects tend to cancel, and interband transitions yield a substantial contribution.