  We have simulated the ultra-high-temperature ceramic zirconium carbide (ZrC)
in order to predict electron and phonon scattering properties, including
lifetimes and transport. Our predictions of heat and charge conductivity, which
extend to 3000 K, are relevant to extreme temperature applications of ZrC.
Mechanisms are identified on a first principles basis that considerably enhance
or suppress heat transport at high temperature, including strain and
anharmonicity. The extent to which boundary confinement and isotope scattering
effects lower thermal conductivity is predicted.
