Electronic structure and optical response of rare-earth semiconductors obtained by semi-local exchange and dynamical mean-field theory

Rare-earth semiconductors such as the rare-earth mononitrides LnN (with Ln=rare-earth) or fluorosulfides LnSF are technologically promising materials with applications ranging from spintronics to optics. Their electronic structure is very challenging for theory, since wide conduction and valence bands coexist with Mott localized rare-earth 4f states. Here, I present a computational method combining a dynamical mean-field theory approach to strong local correlations with a perturbative application of the semi-local modified Becke-Johnson exchange potential to correct the semiconducting gap. In this approach, the on-site Coulomb interaction in the 4f shell is evaluated from first principles. I apply this method to calculate the electronic structure and optical response of the rare-earth mononitrides LnN and the rare-earth fluorosulfides LnSF, which are prospective spintronics and pigment materials, respectively. I show that the employed method can reliably predict their electronic spectral function as well as the evolution of the optical absorption edge in the investigated compounds.