Oxygen Exchange in Uranyl Hydroxide via Two “Nonclassical” Ions
Bibliographic record
Abstract
A recently proposed pathway for the scrambling of axial (uranyl) and equatorial O atoms in [UO(2)(OH)(4)](2-) (1) is refined using Car-Parrinello molecular dynamics (CPMD) simulations in an explicit solvent (water) and with model counterions (NH(4)(+)). According to constrained CPMD/BLYP simulations and thermodynamic integration, 1 can be deprotonated to [UO(3)(OH)(3)](3-) with a T-shaped UO(3) group (DeltaA = 7.1 kcal/mol), which in turn can undergo a solvent-assisted proton transfer via a cis-[UO(2)(OH)(4)](2-).OH(-) complex and a total overall barrier of DeltaA(double dagger) = 12.5 kcal/mol. According to computed relative energies of trans- and cis-[UO(2)(OH)(4)](2-) in the gas phase and in a polarizable continuum, "pure" functionals such as BLYP underestimate this overall barrier somewhat, and estimates of DeltaA(double dagger) approximately 16 and 17 kcal/mol are obtained at the B3LYP and CCSD(T) levels, respectively, in excellent agreement with the experiment.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".