The phase transitions and electronic structures of crystalline BeF2 under high-pressure: First-principle calculations

The high-pressure behaviors of crystalline BeF2 are investigated theoretically by using first-principles plane-wave pseudopotential density functional theory within the local density approximation (LDA). The results demonstrate that the sequence of the pressure-induced phase transitions of BeF2 under 50 GPa is from the α-quartz-type, to coesite-type, rutile-type, and α-PbO2-type structures. Moreover, the electronic properties of BeF2 with different crystal structures are analyzed. The results show that the electronic structures of BeF2 are fairly insensitive to the particular crystal structures, which are determined mainly by the BeF4 tetrahedron (or BeF6 octahedra). At last, the effects of pressure on the electronic structures of BeF2 are discussed. The band gap of BeF2 is found to become broader with increase of pressure.