A charge-optimized many-body potential for the U-UO2-O 2 system

Yangzhong Li, Tao Liang, Susan B. Sinnott, Simon R. Phillpot

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19 Scopus citations

Abstract

Building on previous charge-optimized many-body (COMB) potentials for metallic α-U and gaseous O2, we have developed a new potential for UO2, which also allows the simulation of U-UO2-O2 systems. The UO2 lattice parameter, elastic constants and formation energies of stoichiometric and non-stoichiometric intrinsic defects are well reproduced. Moreover, this is the first rigid-ion potential that produces the correct deviation of the Cauchy relation, as well as the first classical interatomic potential that is able to determine the defect energies of non-stoichiometric intrinsic point defects in UO2 with an appropriate reference state. The oxygen molecule interstitial in the α-U structure is shown to decompose, with some U-O bonds approaching the natural bond length of perfect UO2. Finally, we demonstrate the capability of this COMB potential to simulate a complex system by performing a simulation of the α-U + O2 → UO2 phase transformation. We also identify a possible mechanism for uranium oxidation and the orientation of the resulting fluorite UO2 structure relative to the coordinate system of orthorhombic α-U.

Original languageEnglish (US)
Article number505401
JournalJournal of Physics Condensed Matter
Volume25
Issue number50
DOIs
StatePublished - Dec 18 2013

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics

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