Insulating gap in FeO: correlations and covalency

TL;DR

This paper investigates the electronic structure of FeO, revealing how different computational approaches and structural distortions influence the insulating gap, and provides new insights into the gap’s origin in 3d monoxides.

Contribution

It offers a comparative analysis of LDA and LDA+U methods on FeO, highlighting the impact of structural distortion and band structure on the insulating gap, and discusses the role of k-dependency of U.

Findings

LDA predicts FeO as an antiferromagnetic metal.

LDA+U opens a Hubbard gap in FeO.

The character of the gap varies with structure and method.

Abstract

We report calculations of the electronic structure of FeO in the LDA and LDA+U approximation with and without rhombohedral distortion. In both cases LDA renders an antiferromagnetic metal, and LDA+U opens a Hubbard gap. However, the character of the gap is qualitatively different in the two structure, and the difference can be traced down to underlying LDA band structure. An analysis of the calculations gives a new insight on the origin of the insulating gap in 3d monoxides and on the role of the k-dependency of U, missing in the contemporary LDA+U method.