Renormalization of effective interactions in a negative charge-transfer insulator

TL;DR

This paper calculates effective interaction parameters for LuNiO3 using first-principles methods, revealing significant screening effects that influence its electronic phases and validating low-energy theories for this negative charge-transfer insulator.

Contribution

It provides a detailed first-principles computation of effective interactions in LuNiO3, including screening effects, and explores the resulting phase diagram with dynamical mean-field theory.

Findings

Effective on-site Coulomb repulsion is strongly reduced by screening.

Long-range interactions are significant and influence electronic properties.

LuNiO3 is metallic in orthorhombic phase and insulating in monoclinic phase.

Abstract

We compute from first principles the effective interaction parameters appropriate for a low-energy description of the rare-earth nickelate LuNiO$_{3}$ involving the partially occupied $e_g$ states only. The calculation uses the constrained random-phase approximation and reveals that the effective on-site Coulomb repulsion is strongly reduced by screening effects involving the oxygen-$p$ and nickel-$t_{2g}$ states. The long-range component of the effective low-energy interaction is also found to be sizeable. As a result, the effective on-site interaction between parallel-spin electrons is reduced down to a small negative value. This validates effective low-energy theories of these materials proposed earlier. Electronic structure methods combined with dynamical mean-field theory are used to construct and solve an appropriate low-energy model and explore its phase diagram as a function of the on-site repulsion and Hund's coupling. For the calculated values of these effective interactions we find, in agreement with experiments, that LuNiO$_{3}$ is a metal without disproportionation of the $e_g$ occupancy when considered in its orthorhombic structure, while the monoclinic phase is a disproportionated insulator.