Point-Defect Optical Transitions and Thermal Ionization Energies from Quantum Monte Carlo Methods: Application to F-center Defect in MgO

TL;DR

This paper introduces a quantum Monte Carlo approach for accurately calculating point defect optical and thermal ionization energies, effectively addressing limitations of density functional theory, demonstrated on F-center defects in MgO with excellent results.

Contribution

The paper presents a novel quantum Monte Carlo method for defect energy calculations that improves accuracy over traditional density functional theory approaches.

Findings

Accurate calculation of F-center defect energies in MgO.

Quantum Monte Carlo overcomes the band gap problem.

Results agree well with experimental data.

Abstract

We present an approach to calculation of point defect optical and thermal ionization energies based on the highly accurate quantum Monte Carlo methods. The use of an inherently many-body theory that directly treats electron correlation offers many improvements over the typically-employed density functional theory Kohn-Sham description. In particular, the use of quantum Monte Carlo methods can help overcome the band gap problem and obviate the need for ad-hoc corrections. We demonstrate our approach to the calculation of the optical and thermal ionization energies of the F-center defect in magnesium oxide, and obtain excellent agreement with experimental and/or other high-accuracy computational results.