  Oxygen vacancies are a common source of excess electrons in complex oxides.
In Mott insulators these additional electrons can induce a metal-insulator
transition (MIT), fundamentally altering the electronic properties of the
system. Here we study the effect of oxygen vacancies in LaTiO3, a prototypical
Mott insulator close to the MIT. We show that the introduction of oxygen
vacancies creates a vacancy-related band immediately below the partially filled
Ti-t2g bands. We study the effect of this additional band on the Mott MIT using
a combination of density functional theory and dynamical mean-field theory
(DFT+DMFT), employing a minimal correlated subspace consisting of effective
Ti-t2g orbitals plus an additional Wannier function centered on the vacancy
site. We find that the Mott insulating state in LaTiO3 is robust to the
presence of the vacancy band, which remains fully occupied even in the presence
of a local Coulomb repulsion.
