First-principles investigations of the ground-state and excited-state properties of BeO polymorphs

An investigation into the structural stabilities and the optoelectronic properties of BeO polymorphs was conducted using first-principles calculations based on density-functional theory. In agreement with experimental and earlier ab initio calculations, we found that the B4 phase is slightly lower in energy than the B3 phase, and that it transforms to the B1 structure at 107 GPa, while the B3-B1 transition occurs at 110 GPa. In addition, we found that BeO has a indirect gap in the B3 structure with a band gap of 9.01 eV and a direct band gap in the B4 and B1 phases with band gaps of 8.58 and 8.12 eV, respectively. Also, we have presented the results of the effective masses. To complete the fundamental characteristics of this compound we have analyzed their linear optical properties such as the dynamic dielectric function and energy-loss function for a wide range of energies 0-35 eV.