Dynamics of Hydrated Uranyl Fluoride
Marie Kirkegaard
Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee
This page shows visualizations of water in between the layers of crystalline uranyl fluoride, created by Marie Kirkegaard in the Bredesen Center for Interdisciplinary Research and Graduate Education at the University of Tennessee.
Uranyl fluoride has a three-layer hexagonal crystal structure that remains intact upon partial hydration. Quasi-elastic neutron scattering results suggest that water diffuses between the weakly bound layers at a rate five time slower than the diffusion of bulk water. In addition, water molecules can become trapped in 'pockets' between the polymerisation units 1. An MD simulation was carried out to model these different water dynamics in the crystal. As shown in the visualization below, the water settled into 'pockets' in the crystal and did not diffuse through the layers. Some jumping between pockets is observed however. This discrepancy with experiment is likely due to the inadequacy of the UFF potentials employed. It may also be true that a greater concentration of water molecules are necessary to witness diffusion.
Color Legend: References
1. A. Miskowiec, B. B. Anderson, A. Huq, E. Mamontov, K. W. Herwig, L. Trowbridge, A Rondinone. Molecular Physics. 114 (1), 61-71 (2016). posted: April 28, 2016.Interactive Structure
updated: April 28, 2016.