Titanium and titanium oxides at the K- and L-edges: validating theoretical calculations of X-ray absorption and X-ray emission spectra with measurements

TL;DR

This study validates the accuracy of ab initio theoretical calculations of X-ray absorption and emission spectra for titanium compounds by comparing them with well-calibrated experimental data, demonstrating the broad applicability of the OCEAN package.

Contribution

It provides a comprehensive validation of the OCEAN ab initio calculations across multiple edges and compounds, confirming their transferability and reliability for electronic structure analysis.

Findings

Theoretical spectra closely match experimental data for Ti and Ti oxides.

OCEAN calculations are transferable across different edges and compounds.

Validated the use of the Bethe-Salpeter equation approach in spectral simulations.

Abstract

Using well-calibrated experimental data we validate theoretical X-ray absorption spectroscopy (XAS) as well as X-ray emission spectroscopy (XES) calculations for titanium (Ti), titanium oxide (TiO), and titanium dioxide (TiO$_2$) at the Ti K- and L-edges as well as O K-edge. XAS and XES in combination with a multi-edge approach offer a detailed insight into the electronic structure of materials since both the occupied and unoccupied states, are probed. The experimental results are compared with ab initio calculations from the OCEAN package which uses the Bethe-Salpeter equation (BSE) approach. Using the same set of input parameters for each compound for calculations at different edges, the transferability of the OCEAN calculations across different spectroscopy methods and energy ranges is validated. Thus, the broad applicability for analysing and interpreting the electronic structure of materials with the OCEAN package is shown.