A magnetic tight-binding model: correlations in ferromagnetic transition metals

Abstract: The estimation of correlations through approximations in an electronic many-body calculation often leads to overestimated or underestimated physical properties. But it is possible to better evaluate and understand the effect of correlations from the charge distribution and a screening effect due to a delocalized s state. This provides an accurate description of the d-band magnetism, unifying a localized and delocalized approach and giving approximate values of the band gap in the monoxides of ferromagnetic transition metals. From a tight-binding calculation, 1.3 eV for bcc iron, 1.5 eV for fcc cobalt and 2.1 eV for fcc nickel are found as Coulomb correlations correcting the magnetic energies of a localized d-band approximation.