Optimized Orthogonal Basis Tight Binding. Application to Iron

The formal link between the linear combination of atomic orbitals approach to density functional theory and two-center Slater-Koster tight-binding models is used to derive an orthogonal $d$-band tight-binding model for iron with only two fitting parameters. The resulting tight-binding model correctly predicts the energetic ordering of the low energy iron-phases, including the ferromagnetic BCC, antiferromagnetic FCC, HCP and topologically close-packed structures. The energetics of test structures that were not included in the fit are equally well reproduced as those included, thus demonstrating the transferability of the model. The simple model also gives a good description of the vacancy formation energy in the nonmagnetic FCC and ferromagnetic BCC iron lattices.