Robustness of electronic screening effects in electron spectroscopies: example of V$_2$O$_5$

TL;DR

This study investigates how local structural distortions in V$_2$O$_5$ influence electronic screening and spectroscopic properties, revealing cancellations that preserve spectral features despite significant band structure changes.

Contribution

It demonstrates the robustness of many-body spectroscopic effects against structural modifications in V$_2$O$_5$, providing insights for spectral analysis and material optimization.

Findings

Screening effects are robust against local distortions.

Spectroscopic features remain stable despite band structure changes.

Structural modifications significantly alter the band structure.

Abstract

In bulk and low-dimensional extended systems, the screening of excitations by the electron cloud is a key feature governing spectroscopic properties. Widely used computational approaches, especially in the framework of many-body perturbation theory, such as the GW approximation and the resulting approximate Bethe-Salpeter equation, are explicitly formulated in terms of the screened Coulomb interaction. In the present work we explore the effect of screening in absorption and electron energy loss spectroscopy, concentrating on the effect of local distortions on the screening and elucidating the resulting changes in the various spectra. Using the layered bulk oxide V$_2$O$_5$ as prototype material, we show in which way local distortions affect the screening, and in which way changes in the screening impact electron energy loss and absorption spectra including excitons. We highlight cancellations that make many-body effects in the spectra very robust with respect to structural modifications, while the band structure undergoes significant changes and the nature of the excitations may also be affected. This yields insight concerning the structure-properties relations that are crucial for the use of V$_2$O$_5$ as energy storage material, and more generally, that may be used to optimize the analysis and the calculation of electronic spectra in complex materials.