Heat and charge transport of H₂O in the deep interior of Uranus

Transport properties govern the pace of thermal evolution and the generation of magnetic fields in the ice giants. We use ab initio molecular dynamics simulations and the Green-Kubo theory of linear response to determine the thermal and electrical conductivity of H₂O, leveraging recently discovered invariance principles in the numerical computation of transport coefficients, and cepstral analysis of the flux time series. We examine the liquid, solid, and superionic phases of H₂O, the latter of which is stable over most of the pressure-temperature regime of the Uranian interior. We use our results to build a model of the thermal evolution of Uranus that explains its hitherto poorly understood low luminosity and the evolution orbits of its moons, and which is consistent with observations of the magnetic field.