Parameter-free hybrid functional based on an extended Hubbard model: DFT+U+V

TL;DR

This paper introduces a parameter-free energy functional within DFT+U+V that self-consistently determines interaction parameters, improving electronic property predictions for diverse materials, including strongly correlated systems.

Contribution

It extends the DFT+U+V functional to self-consistently compute on-site and intersite interactions, enabling more accurate ab initio studies of complex materials.

Findings

Improved electronic properties for a wide range of materials.

Self-consistent calculation of Hubbard U, Hund J, and intersite V.

Potential to develop new hybrid functionals and study strongly correlated systems.

Abstract

In this article, we propose an energy functional at the level of DFT+U+V that allows us to compute self-consistently the values of the on-site interaction, Hubbard U and Hund J, as well as the intersite interaction V. This functional extends the previously proposed ACBN0 functional [Phys. Rev. X 5, 011006 (2015)] including both on-site and intersite interactions. We show that this ab initio self-consistent functional yields improved electronic properties for a wide range of materials, ranging from $sp$ materials to strongly-correlated materials. This functional can also be seen as an alternative general and systematic way to construct parameter-free hybrid functionals, based on the extended Hubbard model and a selected set of Coulomb integrals, and might be used to develop novel approximations. By extending the DFT+U method to materials where strong local and nonlocal interactions are relevant, this work opens the door to the ab initio study the electronic, ionic, and optical properties of a larger class of strongly correlated materials in and out of equilibrium.