Large crystal local-field effects in the dynamical structure factor of rutile TiO2

TL;DR

This study combines ab initio calculations and x-ray scattering experiments to reveal significant crystal local-field effects in rutile TiO2, affecting its excitation spectra and electronic structure interpretation.

Contribution

It demonstrates the presence of large crystal local-field effects in rutile TiO2 and their impact on the dynamical structure factor, supported by both theory and experiment.

Findings

Large crystal local-field effects cause a sharp loss peak at 14 eV.

The effects show a non-monotonic dependence on wave vector.

Impact on excitation spectra is more pronounced than in transition metals.

Abstract

We present ab initio time-dependent-density-functional calculations and non-resonant inelastic x-ray scattering measurements of the dynamical structure factor of rutile TiO2. Our calculations are in good agreement with experiment and prove the presence of large crystal local-field effects below the Ti M-edge, which yield a sharp loss peak at 14 eV whose intensity features a remarkable non-monotonic dependence on the wave vector. These effects, which impact the excitation spectra in the oxide more dramatically than in transition metals, provide a signature of the underlying electronic structure.