Localized and Itinerant States in Lanthanide Oxides United by GW @ LDA plus U

Many-body perturbation theory in the GW approach is applied to lanthanide oxides, using the local-density approximation plus a Hubbard U correction (LDA+U) as the starting point. Good agreement between the G(0)W(0) density of states and experimental spectra is observed for CeO2 and Ce2O3. Unlike the LDA+U method G(0)W(0) exhibits only a weak dependence on U in a physically meaningful range of U values. For the whole lanthanide sesquioxide (Ln(2)O(3)) series G(0)W(0) @ LDA+U reproduces the main features found for the optical experimental band gaps. The relative positions of the occupied and unoccupied f states predicted by G(0)W(0) confirm the experimental conjecture derived from phenomenological arguments.