Two-band second moment model for transition metals and alloys

A semi-empirical formalism based on the second moment tight-binding approach, considering two bands is presented for deriving interatomic potentials for magnetic d-band materials. It incorporates an empirical local exchange interaction, which accounts for magnetic effects without increasing the computing time required for force evaluation. The consequences of applying a two-band picture to transition metal alloys and transition metal impurities is examined, which combined with evidence from ab initio calculations leads to some surprisingly simplifying conclusions.