Quasiparticle self-consistentGWmethod applied to localized4felectron systems

Abstract

Rare-earth pnictides possess unique electronic and magnetic properties that make them interesting for both fundamental and practical reasons. We apply the quasiparticle self-consistent $GW$ $(\mathrm{QS}GW)$ method to the rare-earth metals Gd and Er and to the rare-earth monopnictides GdN, EuN, YbN, GdAs, and ErAs. $\mathrm{QS}GW$ is unique in that it automatically takes into account both $spd$ and $f$ electrons in a single, unified framework without any materials-dependent parameters or special treatment of the $f$ electrons. It enables us to examine approximations behind the standard local density $\text{approximation}+U$ and self-interaction corrected approaches. $\mathrm{QS}GW$ reproduces the experimental occupied $4f$ levels well, though the unoccupied levels are a little overestimated. Properties of the Fermi surface responsible for electronic properties---governed by the $spd$ electrons---are in good agreement with available experimental data. GdN is predicted to be very near a critical point of a metal-insulator transition.