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

Abstract

In this paper, we propose an energy functional at the level of DFT + U + V that allows us to compute selfconsistently the values of the onsite interaction, Hubbard U and Hund J, as well as the intersite interaction V. This functional extends the previously proposed ACBN0 functional [L. A. Agapito et al., Phys. Rev. X 5, 011006 (2015)] including both onsite 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.

Extensive Benchmarking of DFT+U Calculations for Predicting Band Gaps

“…DFT+U is only marginally more expensive than DFT within LDA or GGA, while significantly improving various properties of materials such as transition-metal compounds. An extension of DFT+U to take into account inter-site Hubbard V interactions (DFT+U+V [35]) was introduced, showing success in describing materials with strong inter-site electronic hybridizations (i.e., covalent interactions) [35][36][37][38][39][40][41]. Finally, there are various methods beyond DFT, including many-body perturbation theory (MBPT) [42] (e.g., GW approximation [43][44][45][46]) and dynamical mean field theory (DMFT) [47][48][49][50][51], which are widely used for predicting optical properties of (strongly) correlated systems.…”

Magnetic Ordering, Anomalous Lifshitz Transition and Topological Grain Boundaries in Two-Dimensional Biphenylene Network

“…Our self-consistent evaluation of Hubbard interactions are U = 5.93 (5.98) eV and V = 3.05 (3.09) eV for p z -orbitals in the square (dimer) unit. These values are comparable to U and V of graphene [11,28]. Unlike graphene where all atoms have the same Hubbard interactions, atoms belonging to different units of BPN lattice have different values.…”

“…A plane-wave basis set with a cutoff energy of 100 Ry is adopted and the ultrasoft pseudopotential [8] is used. To consider Coulomb interaction beyond the GGA, we used a newly devel-oped DFT+U +V method exploiting the self-consistent evaluation [9][10][11] of the on-and inter-site Hubbard interactions (U and V ) [12]. We consider V between the nearest neighbors (n.n.…”

“…The method enable us to include Coulomb interaction in a similar level of GW approximations with a significantly reduced computational cost [10][11][12][13]. We note that this method captures the effects of Coulomb interaction in 2D crystals such as black phosphorous [10] and graphene [11] very well.…”

“…The magnetic state may stabilize by an enhanced anisotropy from external fields or substrate. So, hereafter, we include the U and V without magnetism to take into account the effects of Coulomb interactions on band energies and group velocities like previous calculations for nonmagnetic materials [10,11].…”