First principle study of mechanical stability and thermodynamic properties of anti-fluorite Li2O and Rb2O under pressure and temperature effect

The structural, elastic and thermodynamic properties of Li2O and Rb2O have been made using FP-APW + lo method as implemented in the WIEN2k code. Some ground state properties such as lattice constant, bulk modulus, pressure derivative of the bulk modulus, and elastic constants are in good agreement with the available experimental results and theoretical data. Moreover, the temperature and pressure thermodynamic properties of Li2O and Rb2O, from 0 to 1200 K are evaluated through the use of quasi-harmonic Debye model. Finally the thermodynamic quantities under high pressure and temperature are also calculated and discussed.