GW+U real-space Green's function calculations of x-ray spectra

TL;DR

This paper introduces a GW+U real-space Green's function method to accurately compute x-ray spectra, incorporating local electron correlation effects for transition metal oxides and cuprates.

Contribution

The paper develops a GW+U approach that combines GW self-energy with a Hubbard U correction for improved x-ray spectra calculations.

Findings

Method yields good agreement with experimental spectra.

Effective in modeling local correlation effects.

Applicable to transition metal oxides and cuprates.

Abstract

The Hubbard model is implemented in real-space Green's function calculations of x-ray spectra using an effective self-energy adapted from the LSDA+U method of Anisimov et al. This self-energy consists of an energy-dependent many-pole approximation to the GW self-energy with an additive correction due to on-site Coulomb repulsion among the partially filled localized-electron states. This leads to a GW+U approach which provides an efficient procedure to account for local correlation effects on x-ray spectra. Results are presented for the spin and angular momentum projected density of states of MnO, NiO, and La_(2-x)Sr_xCuO_4 (LSCO), for the K-edge x-ray spectra of O atoms in MnO and NiO, and the unoccupied electronic states and O K-edge spectra of undoped LSCO. The method is found to yield reasonable agreement with experiment.