A first principles molecular dynamics simulation of the hydrated magnesium ion

First principles molecular dynamics has been used to investigate the solvation of Mg²⁺ in water. In agreement with experiment, we find that the first solvation shell around Mg²⁺ contains six water molecules in an octahedral arrangement. The electronic structure of first solvation shell water molecules has been examined with a localized orbital analysis. We find that water molecules tend to asymmetrically coordinate Mg²⁺ through one of the oxygen lone pair orbitals and that the first solvation shell dipole moments increase by 0.2 Debye relative to pure liquid water.