Abstract
We evaluate the heat capacity of actinide dioxides using first-principles density functional theory (DFT). The heat capacity of actinide dioxides mainly originates from lattice vibrations, and the second largest contribution is the Schottky heat capacity, which is caused by the electronic excitation on actinide atoms. The lattice heat capacity is evaluated thorough the first-principles phonon calculation using DFT, and the Schottky heat capacity is calculated with crystal field potentials based on DFT. We obtain the calculated heat capacity of UO_2 and PuO_2 in good agreement with measurements.
