title: An improved interatomic potential for xenon in UO2: a combined density functional theory/genetic algorithm approach.
abstract: We have created an improved xenon interatomic potential for use with existing UO2 potentials. This potential was fit to density functional theory calculations with the Hubbard U correction (DFT + U) using a genetic algorithm approach called iterative potential refinement (IPR). We examine the defect energetics of the IPR-fitted xenon interatomic potential as well as other, previously published xenon potentials. We compare these potentials to DFT + U derived energetics for a series of xenon defects in a variety of incorporation sites (large, intermediate, and small vacant sites). We find the existing xenon potentials overestimate the energy needed to add a xenon atom to a wide set of defect sites representing a range of incorporation sites, including failing to correctly rank the energetics of the small incorporation site defects (xenon in an interstitial and xenon in a uranium site neighboring uranium in an interstitial). These failures are due to problematic descriptions of Xe-O and/or Xe-U interactions of the previous xenon potentials. These failures are corrected by our newly created xenon potential: our IPR-generated potential gives good agreement with DFT + U calculations to which it was not fitted, such as xenon in an interstitial (small incorporation site) and xenon in a double Schottky defect cluster (large incorporation site). Finally, we note that IPR is very flexible and can be applied to a wide variety of potential forms and materials systems, including metals and EAM potentials.
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Thompson
authors.forename: Bryce
authors.initials: B
authors.lastname: Meredig
authors.forename: C
authors.initials: C
authors.lastname: Wolverton
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D008956:Models, Chemical; D008958:Models, Molecular; D011789:Quantum Theory; D017974:Uranium Compounds / Q000737:chemistry*; D014978:Xenon / Q000737:chemistry*
chemical_list: D017974:Uranium Compounds; D014978:Xenon; C047385:uranium oxide