First-principles study of structural stabilities, electronic and elastic properties of BaF2 under high pressure

A theoretical investigation on the structural stabilities, electronic and elastic properties of BaF2 under high pressure is conducted using first-principles calculations based on density functional theory (DFT) with the plane wave basis set as implemented in the CASTEP code. Our results demonstrate that the sequence of the pressure-induced structure transition of BaF2 is from the fluorite (β) structure to the PbCl2-type (α) structure, to the Ni2In-type (γ) structure. The transition pressures are 2.83 and 12.7 GPa, respectively. The energy gap increases with pressure in β and α structures, then begin to decreases in γ structure above 60 GPa. The band gap overlap metallization, however, does not occur up to 210 GPa. The pressure effect on the elastic properties of β-BaF2 is investigated.