Molecular dynamics simulation of trivalent europium in aqueous solution: A study on the hydration shell structure

As a prelude to a spectroscopic investigation of doped wet gels, we have made molecular dynamics simulations of a very dilute EuCl3 solution. The symmetry properties of the first hydration shell of Eu3+ have been determined. The 8 water molecules of this shell are roughly arranged according to the square antiprism D4d pseudo-symmetry. Though the arrangement of oxygens is little distorted from regular positions, the orientation of the water molecules themselves is found to be not so well organized at room temperature.