Combination of optical properties acquired by first principles calculations with the empirical Tauc method for determining the band gap energy of alkaline-earth metal oxides: MO (M = Be, Mg, Ca, Sr, Ba)

In this paper, we have investigated the structural, electronic and optical properties of alkaline earth oxides MO (M = Be, Mg, Ca, Sr, Ba) using the full-potential linearized augmented plane wave method (FP-LAPW) within the framework of density functional theory (DFT), as implemented in the Wien2k package within the generalized gradient approximation (GGA) and GGA plus Tran and Blaha modified Becke and Johnson potential (TB-mBJ) for treating the exchange and correlation effects. The main objective of this work is to introduce the first principal calculations used for the determination of the optical parameters of alkaline-earth metal oxide materials before introducing them into the experimental Tauc formula to determine the band gap energy of both direct and indirect bang gap semiconductors. The obtained results are of great interest regarding the convergence of the obtained band gap energies using the combined method compared to several research works.