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

Published online by Cambridge University Press:  07 February 2012

Raymond Atta-Fynn ,
Eric J. Bylaska  and
Wibe A. de Jong
Raymond Atta-Fynn
Affiliation:
Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352
Eric J. Bylaska
Affiliation:
Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352
Wibe A. de Jong
Affiliation:
Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352
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Abstract

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.

Keywords

actinidewatersimulation
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1383: Symposium A – Material Challenges in Current and Future Nuclear Technologies , 2012 , mrsf11-1383-a07-06
Copyright
Copyright © Materials Research Society 2012

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References

REFERENCES

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