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

Nicolas Tancogne-Dejean,Angel Rubio

doi:10.1103/physrevb.102.155117

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.

Highlights

During the last few decades, density functional theory (DFT) has emerged as one of the most reliable and efficient numerical methods to simulate a wide range of materials
It is well known that the most employed local and semilocal functionals suffer from many problems, in particular, the so-called “delocalization problem,” which prevents a practical application of using DFT to materials where strong local electron-electron correlations are taking place [1,2]
The nodal-line semimetals exhibit strong nonlocal correlations [31,32], which are not captured by a local Hubbard U as used in DFT + U

Summary

Introduction

During the last few decades, density functional theory (DFT) has emerged as one of the most reliable and efficient numerical methods to simulate a wide range of materials. It is well known that the most employed local and semilocal functionals suffer from many problems, in particular, the so-called “delocalization problem,” which prevents a practical application of using DFT to materials where strong local electron-electron correlations are taking place [1,2]. In order to overcome this problem, one can rely on the well-established dynamical mean field theory (DMFT) [3,4], and its extensions such as DFT + DMFT or GW + DMFT, which have become the state-of-the-art methods to treat strongly correlated materials [5].

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Conclusion