A DFT study of ZnO, Al2O3 and SiO2; combining X-ray spectroscopy, chemical bonding and Wannier functions

Abstract

The electronic properties of a group of oxides with important technological applications were studied performing ab initio calculations. Al2O3 is an important ceramic and catalyst, suitable insulator for electronic applications and nano scale access memory. SiO2 is important from both geological and materials science point of view. Pure and doped ZnO structures have direct industrial applications in lasers, sensors, and infra-red and luminescence sensitive devices.A Full Potential Linearized Augmented Plane Waves (FP-LAPW) method within the Density Functional Theory (DFT) formalism was applied to study electronic properties of these oxides and different post-processing tasks as contour plots of electronic charge density, projected densities of states, band structure, Bader's method and Maximally Localized Wannier Functions were used to analyse the electronic charge transfer and bonding properties of the systems. The positions of these Wannier functions, shown in histograms and 3D plots, opened the possibility to calculate the bonding ionicity trend of materials. We report X-ray spectra obtained from self consistent ab initio calculations. K and L2,3 edges were calculated including the fractional electronic core-hole and double core-hole providing similar features as in the reported experimental X-ray absorption near edge structure (XANES).