Correlation effects in the ground-state charge density of Mott insulating NiO: A comparison ofab initiocalculations and high-energy electron diffraction measurements

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 ab initio approaches to the electronic structure of strongly correlated metal oxides are in accord with experimental observations. The generalized gradient approximation and the local spin density approximation corrected by the Hubbard U term 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.