First-principles calculations of electronic structures and response functions of hexagonal BaAl2O4

Using meta generalized gradient approximations (meta-GGA) to describe the exchange–correlation functional within the framework of density functional theory, we performed first-principles calculations on the electronic structures and response functions of hexagonal BaAl2O4. The electronic structures (band structures, density of states) and response functions (dielectric function, refractive index function, extinction coefficient function and absorption coefficient function) are presented for hexagonal BaAl2O4. It is found that: (i) the bandgap value derived via the meta-GGA (6.40 eV) is in excellent agreement with the experimental value of BaAl2O4 (6.47 eV); and (ii) the calculated absorption coefficient function shows that hexagonal BaAl2O4 exhibits noticeable absorption only when the wavelength of incident photons is less than 194 nm (hν > 6.40 eV), which is consistent with the synchrotron radiation excitation spectrum. Although a complete and reliable description of the electronic structures and optical properties is still on the way, our results have demonstrated that the electronic structures and optical properties derived from the density functional theory based first-principles calculations can be used with reasonable reliability to interpret the optical features of hexagonal BaAl2O4.