First-principles calculations of the electronic structure and spectra of strongly correlated systems: the<b>LDA</b>+<i>U</i>method

TLDR

The paper introduces a generalization of the LDA method to accurately describe Mott insulators in strongly correlated systems. The LDA+U method incorporates orbital‑dependent Coulomb and exchange interactions and, being parameter‑free, serves as a first‑principles approach. Applied to transition metal and rare‑earth compounds, LDA+U improves energy gaps, magnetic moments, exchange parameters, and correctly predicts orbital polarization, Jahn‑Teller distortions, and polaron formation.

Abstract

A generalization of the local density approximation (LDA) method for systems with strong Coulomb correlations is described which gives a correct description of the Mott insulators. The LDA+U method takes into account orbital dependence of the Coulomb and exchange interactions which is absent in the LDA. The scheme can be regarded as a `first-principles' method because there are no adjustable parameters. When applied to the transition metal and rare-earth metal compounds, the LDA+U method gives a qualitative improvement compared with the LDA not only for excited-state properties such as energy gaps but also for ground-state properties such as magnetic moments and interatomic exchange parameters. The orbital-dependent rotationally invariant LDA+U potential gives a correct orbital polarization and a corresponding Jahn - Teller distortion as well as polaron formation.