Optimized Orthogonal Basis Tight Binding. Application to Iron

TL;DR

This paper develops a simple, orthogonal $d$-band tight-binding model for iron with only two parameters, accurately predicting phase energetics and vacancy formation energies, demonstrating high transferability.

Contribution

It introduces a novel orthogonal tight-binding model for iron derived from density functional theory, with only two fitting parameters, improving predictive accuracy and transferability.

Findings

Accurately predicts energetic ordering of iron phases.

Reproduces energetics of test structures not in the fit.

Provides good estimates of vacancy formation energies.

Abstract

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.