First-principles calculations for elastic properties of the rocksalt structure MgO

The thermoelasticity of rocksalt (RS) structure MgO is investigated by ab initio plane-wave pseudopotential density functional theory method and the quasi-harmonic Debye model. The obtained lattice constant, aggregate elastic moduli, pressure derivative of isothermal bulk modulus and elastic constants are well consistent with the experimental data and other theoretical results. Moreover, the pressure dependences of individual elastic modulus at 300 and 800K are also discussed. It is shown that, at 300K, the Debye temperatures from our obtained elastic constants are well consistent with other theoretical results. The Debye temperature increases nonlinearly with increasing pressure.