Ab Initio Study of the Electronic and Optical Properties of ZnO and BeO: First Principles Calculations

Abstract

The ab initio pseudopotential method is based on Density Functional Theory (DFT), in which the Generalized Gradient Approximation (GGA) according to the scheme described by Perdew-Burke-Ernzerhof (PBE) and the Local Density Approximation (LDA) according to the scheme described by Ceperly-Alder (CA) are used. The method is realized utilizing the Siesta program to study the structural and electronic properties of the wurtzite phase of zinc oxide (ZnO) and beryllium oxide (BeO) compounds. Indeed, it is a useful method to predict the crystal structures of ZnO and BeO. Actually, the calculated structural parameters of these compounds are consistent with the available experimental data, so these results can be considered as a good prediction. Both the lattice constants and band gaps at zero pressure are found to be consistent with previous theoretical and experimental results. In addition, the bond length is verified and compared with that of the previous work. The band structure results calculated by GGA are compared with those obtained using LDA, where the approximated values turn out to be the most accurate. The electronic properties, especially the total density of states (TDOS), show the process of electron density distribution in the region close to the Fermi level for both compounds. Comparison of the calculated lattice parameters and all electronic properties with the available experimental values reveals their compatibility. These results are in good agreement with the theoretical results.