First principles study on the structural and optical properties of the high-pressure ZnO phases

A new high-pressure tetragonal phase (BB10) of ZnO is investigated with an ab initio   calculation based on density functional theory and is compared with the cubic BB1 (rocksalt structure) and BB2 (CsCl structure) phases at high pressure. It is found that the BB10 phase has a more covalent nature than the BB2 phase. The BB1, BB2, and BB10 phases are semiconductors and their band gap energies are determined to be 3.73, 3.15, and 3.27 eV, respectively. The BB10 phase has a similar optical response to the BB2 phase, but not the BB1 phase. The similarity of dielectric function between BB10 and BB2 phases are the result of the similar profiles of electronic density of state.

► A new high-pressure tetragonal phase (BB10) of ZnO has a more covalence nature than BB2 phases at high pressure.
► BB1, BB2, and BB10 phases are semiconductors and band gap energies are determined to be 3.73, 3.15, and 3.27 eV, respectively.
► BB10 phase has a similar optical response to the BB2 phase, but not the BB1 phase.