Tight-binding model: correction of the d-band approximation

The electronic structure, when restricted to the d-band approximation, is a computational model that is both efficient and useful for describing transition metals. In the absence of considering delocalized sp-states, this approximation gives rise to incorrect surface energies, binding energies, and an inaccurate description of ferromagnetic transition metals. The present work compares the complexity of implementing corrections with the possibility of using an accurate sp-d approach. Basic force fields based on the second moment approximation continue to be utilized for the description of interactions in transition metals. In contrast, the present study proposes an elementary and more accurate interatomic potential based on hopping parameters depending on distances. The charge distribution and the Stoner model are also analyzed to provide appropriate corrections to the tight-binding picture used to describe ferromagnetic metals and alloys.