Ab-Initio Calculations of Density of States for Ti-Oxide

Abstract

Electron energy-loss spectroscopy (EELS) has been shown to be a powerful tool to determine not only the chemistry, but also the electronic and atomic structure at grain boundaries by analysing the energy-loss near-edge structure (ELNES). However, as the experimental ability to obtain quality spectra from interfaces with high-spatial resolution is relatively new, the interpretation of ELNES has been mostly qualitative. Here we discuss the ability of ab-initio density of state calculations to perform detailed quantitative analysis at interfaces.In this methodology, ignoring any multiparticle effects such as excitons, the ELNES can be described as the symmetry projected density of states (DOS) and a matrix element varying slowly with energy. The calculated DOS, which best reproduce the experimental ELNES, are obtained using density functional theory (DFT) in the local density approximation (LDA) (i.e.: Weng et al.). Traditionally, because a high number of atoms (> 60) is needed to reproduce the periodicity of interface structures, more approximate methods such as the real-space multiple scattering method3 and its equivalent in reciprocal space (KKR-method) were used.