First-principles thermal equation of state of tungsten carbide

► We predict the thermal equation of state of tungsten carbide from first-principles. ► Electronic free energy anisotropy also determines the equilibrium shape of WC. ► Anisotropic compressibility and isotropic thermal expansivity coexist in WC. ► Mie-Grüneisen-Debye formalism is not of sufficient accuracy for WC. ► Metallic W-W bonding also plays an important role in WC.