Self-consistent DFT+U method for real-space time-dependent density functional theory calculations

TL;DR

This paper presents an implementation of a self-consistent DFT+U method within real-space TDDFT, enabling improved simulations of the optical and electronic properties of correlated materials, including response functions and non-collinear spins.

Contribution

The authors developed and tested a self-consistent DFT+U approach within real-space TDDFT, extending it to response functions and non-collinear spins, with validation on various materials.

Findings

Good agreement of results with previous studies on electronic and structural properties.

Self-consistent U and J values align with literature.

Improved optical properties over empirical TDDFT+U schemes.

Abstract

We implemented various DFT+U schemes, including the ACBN0 self-consistent density-functional version of the DFT+U method [Phys. Rev. X 5, 011006 (2015)] within the massively parallel real-space time-dependent density functional theory (TDDFT) code Octopus. We further extended the method to the case of the calculation of response functions with real-time TDDFT+U and to the description of non-collinear spin systems. The implementation is tested by investigating the ground-state and optical properties of various transition metal oxides, bulk topological insulators, and molecules. Our results are found to be in good agreement with previously published results for both the electronic band structure and structural properties. The self consistent calculated values of U and J are also in good agreement with the values commonly used in the literature. We found that the time-dependent extension of the self-consistent DFT+U method yields improved optical properties when compared to the empirical TDDFT+U scheme. This work thus opens a different theoretical framework to address the non equilibrium properties of correlated systems.