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Density Functional Calculations of the Structure of Near-Surface Oxygen Vacancies and Electron Localization on CeO2(111)

Journal Article · · Physical Review Letters
One of the most topical issues surrounding oxygen vacancies on CeO{sub 2}(111) is the relative stability of surface and subsurface defects. Using density-functional theory (DFT) with the HSE06 (Heyd-Scuseria-Ernzerhof) hybrid functional as well as the DFT+U approach (where U is a Hubbard-like term describing the on-site Coulomb interactions), we find subsurface vacancies with (2 x 2) periodicity to be energetically more favorable by 0.45 (HSE06), 0.47 [PBE+U (Perdew-Burke-Ernzerhof functional)], and 0.22 eV [LDA+U (local density approximation)]. The excess electrons localize not on Ce ions which are the nearest neighbor to the defect as priorly suggested, but instead on those that are next-nearest neighbors. The excess-electron distribution and the preference for subsurface vacancies are explained in terms of defect-induced lattice relaxation effects.
Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO.
Sponsoring Organization:
USDOE
DOE Contract Number:
AC36-99GO10337
OSTI ID:
951225
Journal Information:
Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 2, 16 January 2009 Vol. 102; ISSN 0031-9007; ISSN PRLTAO
Country of Publication:
United States
Language:
English