Modeling ofCeO2,Ce2O3, andCeO2−xin theLDA+Uformalism

Abstract

The electronic structure and thermodynamic properties of $\mathrm{Ce}{\mathrm{O}}_{2}$ and ${\mathrm{Ce}}_{2}{\mathrm{O}}_{3}$ have been studied from first principles by the all-electron projector-augmented-wave (PAW) method, as implemented in the ab initio total-energy and molecular-dynamics program VASP (Vienna ab initio simulation package). The local density approximation $(\mathrm{LDA})+U$ formalism has been used to account for the strong on-site Coulomb repulsion among the localized Ce $4f$ electrons. We discuss how the properties of $\mathrm{Ce}{\mathrm{O}}_{2}$ and ${\mathrm{Ce}}_{2}{\mathrm{O}}_{3}$ are affected by the choice of $U$ as well as the choice of exchange-correlation potential, i.e., the local density approximation or the generalized gradient approximation. Further, reduction of $\mathrm{Ce}{\mathrm{O}}_{2}$, leading to formation of ${\mathrm{Ce}}_{2}{\mathrm{O}}_{3}$ and $\mathrm{Ce}{\mathrm{O}}_{2\ensuremath{-}x}$, and its dependence on $U$ and exchange-correlation potential have been studied in detail. Our results show that by choosing an appropriate $U$ it is possible to consistently describe structural, thermodynamic, and electronic properties of $\mathrm{Ce}{\mathrm{O}}_{2}$, ${\mathrm{Ce}}_{2}{\mathrm{O}}_{3}$, and $\mathrm{Ce}{\mathrm{O}}_{2\ensuremath{-}x}$, which enables modeling of redox processes involving ceria-based materials.