Abstract: The structure parameters and some thermodynamic functions for UO2, UC2, UCO are calculated using ab initio method. The vibration energies Ev, vibration and electronic entropies Sev for solid U are calculated based on Debye’s theories for crystal vibration. Thus the formation thermodynamic functions ΔHfΘ、ΔSfΘ and ΔGfΘ for UO2, UC2 and UCO compound are obtained. Results show that UO2 is stable, while UC2 and UCO are unstable.

Key words: UO₂, UC₂, UCO, Thermodynamic function