Optical properties, electron-phonon coupling, and Raman scattering of vanadium ladder compounds

TL;DR

This paper uses ab initio calculations to analyze the electronic structure, optical properties, phonon modes, and Raman scattering of vanadium ladder compounds, showing good agreement with experimental data.

Contribution

It provides a comprehensive first-principles study of electronic, phononic, and optical properties of vanadium ladder compounds, including dielectric functions and Raman intensities.

Findings

Dielectric function matches experimental data

Phonon frequencies agree with experiments

Raman scattering intensities are accurately predicted

Abstract

The electronic structure of two V-based ladder compounds, the quarter-filled NaV$_2$O$_5$ in the symmetric phase and the iso-structural half-filled CaV$_2$O$_5$ is investigated by ab initio calculations. Based on the bandstructure we determine the dielectric tensor $\epsilon(\omega)$ of these systems in a wide energy range. The frequencies and eigenvectors of the fully symmetric A$_{g}$ phonon modes and the corresponding electron-phonon and spin-phonon coupling parameters are also calculated from first-principles. We determine the Raman scattering intensities of the A$_g$ phonon modes as a function of polarization and frequency of the exciting light. All results, i.e. shape and magnitude of the dielectric function, phonon frequencies and Raman intensities show very good agreement with available experimental data.