Third-generation muffin-tin orbitals

TL;DR

This paper introduces third-generation muffin-tin orbitals (MTOs), demonstrating their ability to generate minimal basis sets and Wannier functions, thereby enhancing chemical understanding in semiconductors.

Contribution

It presents a novel formulation of 3rd-generation MTOs that can be downfolded to smaller basis sets and used to generate Wannier functions a priori.

Findings

MTOs can be downfolded to smaller basis sets like sp^3d^10 and sp^3.

Wannier functions can be generated a priori for isolated bands.

Wannier-like MTOs can be generated for overlapping bands.

Abstract

By the example of sp^3-bonded semiconductors, we illustrate what 3rd-generation muffin-tin orbitals (MTOs) are. We demonstrate that they can be downfolded to smaller and smaller basis sets: sp^3d^10,sp^3, and bond orbitals. For isolated bands, it is possible to generate Wannier functions a priori. Also for bands, which overlap other bands, Wannier-like MTOs can be generated a priori. Hence, MTOs have a unique capability for providing chemical understanding.