INSULATING GAP IN FEO - CORRELATIONS AND COVALENCY

We report calculations of the electronic structure of FeO in the local -density approximation (LDA) and LDA+U approximation with and without rhombohedral distortion. In both cases LDA renders an antiferromagneti c metal, and LDA+U opens a Hubbard gap. However, the character of the Sap is qualitatively different in the two structures, and the differen ce can be traced down to the underlying LDA band structure. An analysi s of the calculations gives insight into the origin of the insulating gap in 3d monoxides and into the role of the k dependency of U, missin g in the contemporary LDA+U method.