LDA+DMFT computation of the electronic spectrum of NiO

TL;DR

This paper uses LDA+DMFT with Wannier functions and QMC to accurately compute NiO's electronic spectrum, energy gap, and magnetic moment, highlighting the role of strong correlations in its insulating behavior.

Contribution

It introduces a material-specific many-body Hamiltonian approach for NiO, demonstrating the effectiveness of LDA+DMFT combined with Wannier functions and QMC in capturing its electronic properties.

Findings

The large insulating gap arises from strong electronic correlations.

Calculated spectrum matches experimental photoemission data.

Magnetic moment in paramagnetic phase aligns with experimental measurements.

Abstract

The electronic spectrum, energy gap and local magnetic moment of paramagnetic NiO are computed by using the local density approximation plus dynamical mean-field theory (LDA+DMFT). To this end the noninteracting Hamiltonian obtained within the local density approximation (LDA) is expressed in Wannier functions basis, with only the five anti-bonding bands with mainly Ni 3d character taken into account. Complementing it by local Coulomb interactions one arrives at a material-specific many-body Hamiltonian which is solved by DMFT together with quantum Monte-Carlo (QMC) simulations. The large insulating gap in NiO is found to be a result of the strong electronic correlations in the paramagnetic state. In the vicinity of the gap region, the shape of the electronic spectrum calculated in this way is in good agreement with the experimental x-ray-photoemission and bremsstrahlung-isochromat-spectroscopy results of Sawatzky and Allen. The value of the local magnetic moment computed in the paramagnetic phase (PM) agrees well with that measured in the antiferromagnetic (AFM) phase. Our results for the electronic spectrum and the local magnetic moment in the PM phase are in accordance with the experimental finding that AFM long-range order has no significant influence on the electronic structure of NiO.