Showing papers by "Fernando Flores published in 2021"

A local-orbital density functional formalism for a many-body atomic Hamiltonian: Hubbard-Hund's coupling and DFT + U functional.

Abstract: In the conventional DFT+U approach, the mean field solution of the Hubbard Hamiltonian associated with the d or f (i σ) electrons of a transition metal atom is used to define the DFT+U potential acting on the i σ-electrons. In this work, by means of a many-body Density Functional solution of a Kanamori Hamiltonian (an extension of the atomic Hubbard Hamiltonian), that takes as independent variables of its DF-solution the orbital occupancies, niσ, of the atomic orbitals, we calculate in a first step the electronic properties for a transition metal atom connected to different channels representing an environment. Then, we use this analysis to introduce a DFT+U potential extending previous proposals to materials with arbitrarily high correlation. In particular, we find that this potential mainly screens the conventional mean field potential contribution, and also yields new terms associated with the number of atomic electrons. Our results show that the atomic correlation effects enhance the role played by the intra-atomic exchange interaction and favor the formation of magnetic solutions.