The electronic structure of the monoclinic structure of Fe3O4 is studied using both the local density approximation (LDA) and the LDA+U. The LDA gives only a small charge disproportionation, thus excluding that the structural distortion should be sufficient to give a charge order. The LDA+U results in a charge disproportion along the c-axis in good agreement with the experiment. We also show how the effective U can be calculated within the augmented plane wave methods.
@article{arxiv.cond-mat/0412560,
title = {Charge order in Magnetite. An LDA+$U$ study},
author = {Georg K. H. Madsen and Pavel Novák},
journal= {arXiv preprint arXiv:cond-mat/0412560},
year = {2016}
}