A Self-consistent DFT+DMFT scheme in the Projector Augmented Wave : Applications to Cerium, Ce2O3 and Pu2O3 with the Hubbard I solver and comparison to DFT+U

TL;DR

This paper presents a self-consistent DFT+DMFT implementation using PAW that accurately computes total energies for f-electron systems, comparing results with DFT+U and highlighting advantages in physical realism and solution stability.

Contribution

It introduces a general, fully self-consistent DFT+DMFT scheme within a plane wave-PAW framework applicable to f-electron systems, using the Hubbard I solver for efficiency.

Findings

DFT+DMFT preserves spin and orbital symmetry unlike DFT+U.

The method yields more physically accurate energies for strongly correlated insulators.

DFT+DMFT reduces unphysical metastable solutions compared to DFT+U.

Abstract

An implementation of full self-consistency over the electronic density in the DFT+DMFT framework on the basis of a plane wave-projector augmented wave (PAW) DFT code is presented. It allows for an accurate calculation of the total energy in DFT+DMFT within a plane wave approach. In contrast to frameworks based on the maximally localized Wannier function, the method is easily applied to f electron systems, such as cerium, cerium oxide (Ce2O3) and plutonium oxide (Pu2O3). In order to have a correct and physical calculation of the energy terms, we find that the calculation of the self-consistent density is mandatory. The formalism is general and does not depend on the method used to solve the impurity model. Calculations are carried out within the Hubbard I approximation, which is fast to solve, and gives a good description of strongly correlated insulators. We compare the DFT+DMFT and DFT+U solutions, and underline the qualitative differences of their converged densities. We emphasize that in contrast to DFT+U, DFT+DMFT does not break the spin and orbital symmetry. As a consequence, DFT+DMFT implies, on top of a better physical description of correlated metals and insulators, a reduced occurrence of unphysical metastable solutions in correlated insulators in comparison to DFT+U.