Screened hybrid functionals applied to ceria: Effect of Fock exchange

Abstract

We investigate how the redox properties of ceria are affected by the fraction of Fock exchange in screened HSE06-based hybrid density functionals, and we compare with $\mathrm{PBE}+U$ results, and with experiments when available. We find that using $\ensuremath{\sim}15%$ Fock exchange yields a good compromise with respect to structure, electronic structure, and calculated reduction energies, and represents a significant improvement over the $\mathrm{PBE}+U$ results. We also investigate the possibility to use a computationally cheaper HSE06//$\mathrm{PBE}+U$ protocol consisting of structure optimization with $\mathrm{PBE}+U$, a subsequent lattice parameter rescaling step, and, finally, a single-point full hybrid calculation. We find that such a composite computational protocol works very well and yields results in close agreement with those where HSE06 was used also for the structure optimization.