title: Exploring Ce3+/Ce4+ cation ordering in reduced ceria nanoparticles using interionic-potential and density-functional calculations.
abstract: The performance of atomistic calculations using interionic potentials has been examined in detail with respect to the structures and energetic stabilities of ten configurational isomers (i.e., distinct Ce3+/Ce4+ cationic orderings) of a low energy octahedral ceria nanoparticle Ce19O32. The outcome of these calculations is compared with the results of corresponding density-functional (DF) calculations employing local and gradient corrected functionals with an additional corrective onsite Coulombic interaction applied to the f-electrons (i.e., LDA+U and GGA+U, respectively). Strikingly similar relative energy ordering of the isomers and atomic scale structural trends (e.g., cation-cation distances) are obtained in both the DF and interionic-potential calculations. The surprisingly good agreement between the DF electronic structure calculations and the relatively simple classical potentials is not found to be due to a single dominant interaction type but is due to a sensitive balance between long range electrostatics and local bonding contributions to the energy. Considering the relatively high computational cost and technical difficulty involved in obtaining charge-localized electronic solutions for reduced ceria using DF calculations, the use of interionic potentials for rapid and reliable preselection of the most stable Ce3+/Ce4+ cationic orderings is of considerable benefit.
authors.affiliation: Departament de Química Física and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Annapaola
authors.initials: A
authors.lastname: Migani
authors.forename: Konstantin M
authors.initials: KM
authors.lastname: Neyman
authors.forename: Francesc
authors.initials: F
authors.lastname: Illas
authors.forename: Stefan T
authors.initials: ST
authors.lastname: Bromley
mesh_terms: D002412:Cations / Q000737:chemistry*; D002563:Cerium / Q000737:chemistry*; D003198:Computer Simulation; D008958:Models, Molecular; D053758:Nanoparticles / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D002412:Cations; D002563:Cerium