Density-functional tight-binding for beginners

TL;DR

This paper provides a comprehensive, beginner-friendly introduction to the density-functional tight-binding (DFTB) method, including derivation, formalism, and practical parametrization techniques, emphasizing its accessibility and utility.

Contribution

It offers a detailed pedagogical guide to DFTB, including derivation, formalism, and practical parametrization methods, aimed at newcomers to the technique.

Findings

Provides practical recipes for parametrization

Details derivation from density-functional theory

Introduces open-source DFTB software package

Abstract

This article is a pedagogical introduction to density-functional tight-binding (DFTB) method. We derive it from the density-functional theory, give the details behind the tight-binding formalism, and give practical recipes for parametrization: how to calculate pseudo-atomic orbitals and matrix elements, and especially how to systematically fit the short-range repulsions. Our scope is neither to provide a historical review nor to make performance comparisons, but to give beginner's guide for this approximate, but in many ways invaluable, electronic structure simulation method--now freely available as an open-source software package, hotbit.