In the present paper, phonon spectrum, thermodynamic properties of thoria have been studied through the ab-initio calculations based on the density functional perturbation theory and density functional theory under QHA as implemented in GIBBS2 code. Also, the QUANTUM ESPRESSO, which is an open-source software package based on the ab initio calculations, was used to investigate the phonon spectrum in several directions. Besides, vibrational heat capacity at constant-volume, phonon entropy, which has been calculated by local density approximation and generalized gradient approximation for exchange and correlation effect, were calculated and then compared with each other. For the vibrational heat capacity at constant-volume, both GGA and LDA approaches led to very similar results.
