Accurate Tight-Binding Hamiltonians for 2D and Layered Materials

TL;DR

This paper introduces a controllable scheme to enhance the accuracy of tight-binding Hamiltonians derived from plane-wave ab initio calculations, enabling better band structure interpolation including unoccupied states.

Contribution

It presents a systematic method to improve tight-binding models by increasing basis set completeness, capturing states previously inaccessible to traditional models.

Findings

Enhanced accuracy in band structure interpolation.

Successful modeling of interlayer and image states.

Applicable to materials with large interstitial regions.

Abstract

We present a scheme to controllably improve the accuracy of tight-binding Hamiltonian matrices derived by projecting the solutions of plane-wave ab initio calculations on atomic orbital basis sets. By systematically increasing the completeness of the basis set of atomic orbitals, we are able to optimize the quality of the band structure interpolation over wide energy ranges including unoccupied states. This methodology is applied to the case of interlayer and image states, which appear several eV above the Fermi level in materials with large interstitial regions or surfaces such as graphite and graphene. Due to their spatial localization in the empty regions inside or outside of the system, these states have been inaccessible to traditional tight-binding models and even to ab initio calculations with atom-centered basis functions.