The optical absorption spectra of V centers in deformed MgO under pressure

TL;DR

This study uses first-principles calculations to analyze how pressure affects the optical absorption spectra of V centers in MgO, revealing a pressure-induced blue shift consistent with experiments.

Contribution

It provides a detailed theoretical investigation of V centers in MgO under pressure, highlighting the importance of defect configuration and hybrid functional calculations for optical properties.

Findings

Absorption peaks at ~2.5 eV for V^0 and ~2.6 eV for V^- at ambient conditions.

Pressure causes a blue shift in the absorption peaks.

Distorted configurations are energetically favorable and influence optical spectra.

Abstract

The electronic structure and optical absorption spectrum of V^{0} and V^{-} center in MgO are investigated using first-principles calculations based on density functional theory. It is demonstrated that the configuration with distortion is energetically favorable in PBE0 functional. The six O atoms around Mg vacancy are non-equivalent due to the distortion. The defect states localized in the band gap are obtained by applying hybrid functional calculations, which is very important for optical properties. At ambient condition, the absorption peak at ~2.5 and ~2.6 eV is assigned to V^{0} and V^{-} center, respectively. With increasing pressure, the absorption peak shows blue shift. The trend is consistent with the experimental observation.