Skip to main content

Free energies and mechanisms of water exchange around Uranyl from first principles molecular dynamics

  • Raymond Atta-Fynn (a1), Eric J. Bylaska (a1) and Wibe A. de Jong (a1)

From density functional theory (DFT) based ab initio (Car-Parrinello) metadynamics, we compute the activation energies and mechanisms of water exchange between the first and second hydration shells of aqueous Uranyl (UO22+) using the primary hydration number of U as the reaction coordinate. The free energy and activation barrier of the water dissociation reaction [UO2(OH2)5]2+(aq) → [UO2(OH2)4]2+(aq) + H2O are 0.7 kcal and 4.7 kcal/mol respectively. The free energy is in good agreement with previous theoretical (-2.7 to +1.2 kcal/mol) and experimental (0.5 to 2.2 kcal/mol) data. The associative reaction [UO2(OH2)5]2+(aq) + H2O → [UO2(OH2)6]2+(aq) is short-lived with a free energy and activation barrier of +7.9 kcal/mol and +8.9 kca/mol respectively; it is therefore classified as associative-interchange. On the basis of the free energy differences and activation barriers, we predict that the dominant exchange mechanism between [UO2(OH2)5]2+(aq) and bulk water is dissociative.

Hide All
1.Richens D. T.The Chemistry of Aqua Ions. Chichester: John Wiley & Sons, 1997.
2.Helm L.; Merbach A. E. Chem. Rev. 2005, 105, 1923.
3.Nichols P.; Bylaska E. J.; Schenter G. K.; de Jong W. A. J. Chem. Phys. 2008, 128, 124507.
4.Neuefeind J.; Soderholm L.; Skanthakumar S. J. Phys. Chem. A 2004, 109, 2733.
5.Soderholm L.; Skanthakumar S.; Neuefeind J. Anal. Bioanal. Chem. 2005, 383, 48.
6.Gutowski K. E., Dixon K. E, D. A.J. Phys. Chem. A 2008, 110, 8840.
7.Spencer S. et al. . J. Phys. Chem. A 1999, 103, 1831.
8.Hay P. J. J. Chem. Phys. 1983, 79, 5469.
9.Vallet V.; Privalov T.; Wahlgren U.; Grenthe I. J. Am. Chem. Soc. 2004, 126, 7766.
10.Bühl M.; Diss R.; Wipff G. J. Am. Chem. Soc. 2005, 127, 13506.
11.Bühl M.; Kabreden H. Inorg. Chem. 2006, 45, 3834.
12.Farkas I.; Bányai I.; Szabó Z.; Wahlgren U.; Grenthe I. Inorg. Chem. 2000, 39, 799.
13.Laio A.; Parrinello M. Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 12562.
14.Laio A.; Gervasio F. L. Rep. Prog. Phys. 2008, 71, 126601.
15.Barducci A.; Bussi G.; Parrinello M. Phys. Rev. Lett. 2008, 100, 020603
16.Car R.; Parrinello M. Phys. Rev. Lett. 1985, 55, 2471.
17.Kohn W.; Sham L. J. Phys. Rev. 1965, 140, A1133.
18.Valiev M. et al. . Comput. Phys. Commun. 2010, 181, 1477.
19.Perdew J. P.; Burke K.; Ernzerhof M. Phys. Rev. Lett. 1996, 77, 3865.
20.Kleinman L.; Bylander D. M. Phys. Rev. Lett. 1982, 48, 1425.
21.Nose S. Mol. Phys. 1984, 52, 255; Hoover, W. G. Phys. Rev. A, 1985, 31, 1695.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

MRS Online Proceedings Library (OPL)
  • ISSN: -
  • EISSN: 1946-4274
  • URL: /core/journals/mrs-online-proceedings-library-archive
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 0
Total number of PDF views: 3 *
Loading metrics...

Abstract views

Total abstract views: 120 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 22nd November 2017. This data will be updated every 24 hours.