First-principles calculations of the elastic constants of the cubic, orthorhombic and hexagonal phases of BaF2

All the elastic constants of cubic, orthorhombic and hexagonal phases of BaF2 have been calculated using first principles methods. We have employed density-functional theory within generalized gradient approximation (GGA) using a plane-wave pseudopotentials method and a plane-wave basis set. The calculated elastic constant values for a cubic phase compare well with recent theoretical and experimental calculations. The bulk modulus derived from the elastic constant calculations of orthorhombic phase of BaF2 is 94.5 GPa and those of hexagonal phase is 161 GPa. These values are in good agreement with experimental data available. Stability of these phases of BaF2 is also estimated in different crystallographic directions.