A combination of density functional and dynamical mean-field theory is applied to the perovskites SrVO3, LaTiO3 and LaVO3. We show that DFT+DMFT in conjunction with the standard fully localized-limit (FLL) double-counting predicts that LaTiO3 and LaVO3 are metals even though experimentally they are correlation-driven ("Mott") insulators. In addition, the FLL double counting implies a splitting between oxygen p and transition metal d levels which differs from experiment. Introducing into the theory an \textit{ad hoc} double counting correction which reproduces the experimentally measured insulating gap leads also to a p-d splitting consistent with experiment if the on-site interaction U is chosen in a relatively narrow range (∼6±1 eV). The results indicate that these early transition metal oxides will serve as critical test for the formulation of a general \textit{ab initio} theory of correlated electron metals.
@article{arxiv.1309.2995,
title = {Covalency and the metal-insulator transition in titanate and vanadate perovskites},
author = {Hung T. Dang and Andrew J. Millis and Chris A. Marianetti},
journal= {arXiv preprint arXiv:1309.2995},
year = {2014}
}