Correlation effects in the ground state charge density of Mott-insulating NiO: a comparison of ab-initio calculations and high-energy electron diffraction measurements

TL;DR

This study compares ab-initio calculations with high-energy electron diffraction measurements to understand how strong correlations in NiO influence its charge density, revealing that certain computational methods align well with experimental data.

Contribution

The paper demonstrates that GGA and LSDA+U methods accurately reproduce experimental charge densities in NiO, highlighting the impact of Ni 3d correlations on covalent bonding.

Findings

GGA and LSDA+U match experimental structure factors closely

Correlations in Ni 3d shell suppress covalent bonding

High-energy electron diffraction effectively probes charge density

Abstract

Accurate high-energy electron diffraction measurements of structure factors of NiO have been carried out to investigate how strong correlations in the Ni 3d shell affect electron charge density in the interior area of nickel ions and whether the new ab-initio approaches to the electronic structure of strongly correlated metal oxides are in accord with experimental observations. The generalized gradient approximation (GGA) and the local spin density approximation corrected by the Hubbard U term (LSDA+U) are found to provide the closest match to experimental measurements. The comparison of calculated and observed electron charge densities shows that correlations in the Ni 3d shell suppress covalent bonding between the oxygen and nickel sublattices.