Hydration structures of U(III) and U(IV) ions from ab initio molecular dynamics simulations

Journal Article · Tue Aug 21 04:00:00 EDT 2012 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4742754· OSTI ID:22098973

Leung, Kevin; Nenoff, Tina M. ^[1]

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1. Sandia National Laboratories, MS 1415, Albuquerque, New Mexico 87185 (United States)

We apply DFT+U-based ab initio molecular dynamics simulations to study the hydration structures of U(III) and U(IV) ions, pertinent to redox reactions associated with uranium salts in aqueous media. U(III) is predicted to be coordinated to 8 water molecules, while U(IV) has a hydration number between 7 and 8. At least one of the innershell water molecules of the hydrated U(IV) complex becomes spontaneously deprotonated. As a result, the U(IV)-O pair correlation function exhibits a satellite peak at 2.15 A associated with the shorter U(IV)-(OH{sup -}) bond. This feature is not accounted for in analysis of extended x-ray absorption fine structure and x-ray adsorption near edge structure measurements, which yield higher estimates of U(IV) hydration numbers. This suggests that it may be useful to include the effect of possible hydrolysis in future interpretation of experiments, especially when the experimental pH is close to the reported hydrolysis equilibrium constant value.

• OSTI ID: 22098973
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 7 Vol. 137; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION
ABSORPTION SPECTROSCOPY
ADSORPTION
CORRELATION FUNCTIONS
DENSITY FUNCTIONAL METHOD
DISSOCIATION
EQUILIBRIUM
FINE STRUCTURE
HYDRATION
HYDROLYSIS
MOLECULAR DYNAMICS METHOD
OXIDATION
REDOX REACTIONS
REDUCTION
SIMULATION
URANIUM COMPOUNDS
X RADIATION
X-RAY SPECTROSCOPY