The thermodynamic properties of lithium peroxide, Li2O2

Recently, Cota et al. gave an improved crystal structure of lithium peroxide. For the sake of investigation of the thermal properties for this structure of Li2O2, the Debye model is adopted in our work. This model combines with the ab initio calculations within local density approximation (LDA) using pseudopotentials and a planewave basis in the framework of density functional theory (DFT), and it takes into account the phononic effects within the quasi-harmonic approximation. We find that our calculated lattice constant using this model is in excellent agreement with the data from Cota et al. Based on the first principles study and the Debye model, the thermal properties including the equation of state, the Debye temperature, the heat capacity and the thermal expansion are obtained in the whole pressure range from 0 to 10 GPa and temperature range from 0 to 500 K.