Effect of Uranyl Ion on Orientation, Dynamics and Hydrogen Bond Dynamics of Nitrate Ion in Aqueous Uranyl Nitrate Solution.

Classical molecular dynamics (MD) simulation was carried out for aqueous UO2(NO3)2 solution with varying concentrations. Our simulation results reveal that with increasing concentration, more NO3- are found in the second coordination shell of UO22+, and in the first coordination shell, UO22+ and NO3- are in the same plane. Water molecules are oriented at 90° with respect to the plane of NO3-. Decrease in diffusivity of NO3- in the first coordination shell of UO22+ results in a significant difference in the VACF of NO3-. At time t = 100 ps or more, UO22+, NO3-, and water show almost identical jump motion as it is seen by the similar peaks appearing in the van Hove correlation function. However, a distinct peak appears at a time delay of t = 1 ps or less. The different distance parameters computed during the hydrogen bond (HB) switching event between water and NO3- have shown that the association of UO22+ with NO3- affects the HB switching event.