$GW$ study of f-shell systems

We have applied the recently developed Quasiparticle Self-Consistent GW (QS$GW$) method to rare-earth metals, rare-earth compounds, and actinide metals. Comparison with the available experimental data shows that this method can successfully describe the electronic structure of these materials within a unified ab-initio theoretical framework. Through this approach we can examine the approximations that enter into the LDA+U method and show ways of improving its implementation. Based on the QS$GW$ bands, a discussion of the role of electronic correlations on the band structure of uranium and plutonium will be presented. Finally, we uncover a completely new effect: a first-order metal-insulator transition in GdN, which is driven by dielectric function changes. This result may explain the ambiguities in the experimental data obtained for this material.