Electronic structure of van der Waals ferromagnet CrI$_{3}$ from self consistent vertex corrected GW approaches

Abstract: Electronic structure of layered van der Waals ferromagnet CrI$_{3}$ is studied with self consistent diagrammatic approaches beyond GW approximation. Considerable improvement in the calculated band gap as compared to the non-self-consistent G0W0 results has been found. Certain spectral features in the valence bands discovered recently by the angle resolved photoemission spectroscopy, are reproduced better when we use full frequency dependent self energy. Density functional theory and quasiparticle self-consistent GW method which are based on frequency-independent self energy are unable to resolve these features. Non-locality effects in the diagrams beyond GW approximation are large for both polarizability and self energy. This finding can potentially have an impact on the development of methods like GW+DMFT.