Correlated electrons in Fe-As compounds: a quantum chemical perspective

TL;DR

This study uses advanced quantum chemical methods to analyze the electronic structure of LiFeAs, revealing high-spin states, significant Coulomb interactions, and orbital degeneracy that influence its metallic and superconducting properties.

Contribution

It provides a detailed quantum chemical analysis of LiFeAs, highlighting the role of electron correlations and orbital degeneracy in its electronic behavior.

Findings

Fe ions have a high-spin S=2 ground state

Orbital degeneracy suggests strong fluctuations and low metallic conductivity

Lowest electron-removal states have As 4p character

Abstract

State-of-the-art quantum chemical methods are applied to the study of the multiorbital correlated electronic structure of a Fe-As compound, the recently discovered LiFeAs. Our calculations predict a high-spin, S=2, ground-state configuration for the Fe ions, which shows that the on-site Coulomb interactions are substantial. Also, orbital degeneracy in the (xz,yz) sector and a three-quarter filling of these levels suggest the presence of strong fluctuations and are compatible with a low metallic conductivity in the normal state. The lowest electron-removal states have As 4p character, in analogy to the ligand hole states in p-type cuprate superconductors.