title: Thermodynamics of tetravalent thorium and uranium complexes from first-principles calculations.
abstract: Enthalpies of formation for the ThX4 and UX4 (X = F, Cl, OH) species have been investigated with density functional theory and coupled-cluster methods. ThX4 molecules are all confirmed as tetrahedral, while all UX4 molecules are predicted to adopt D2d symmetry using density functional theory. Multireference coupled cluster approaches confirm the D2d symmetry for UF4. The bonding is mostly ionic, and predicted formation energies for the halogen species show good agreement with experiment. Our calculated hydration energy of UF4 (-54.0 kcal/mol) is in very good agreement with the experimental data (-54.8 kcal/mol). We predict CCSD(T) formation energies of ΔfG[U(OH)4(g)] = -286.3 kcal/mol and ΔfG[U(OH)4(aq)] = -318.7 kcal/mol. ΔfG[U(OH)4(aq)] is 21 kcal/mol less stable than the established experimental thermodynamic data.
authors.affiliation: Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington, United States.
authors.forename: Donald F
authors.initials: DF
authors.lastname: Johnson
authors.forename: Kiran
authors.initials: K
authors.lastname: Bhaskaran-Nair
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Bylaska
authors.forename: Wibe A
authors.initials: WA
authors.lastname: de Jong
mesh_terms: D009942:Organometallic Compounds / Q000737:chemistry*; D011789:Quantum Theory; D013816:Thermodynamics; D013910:Thorium / Q000737:chemistry*; D014501:Uranium / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D014501:Uranium; D013910:Thorium