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QMCF-MD simulations have been carried out for Pr(III), Nd(III), Pm(III) and Sm(III) ions in aqueous environment, employing ab initio quantum mechanical treatment for ion, first and second hydration shell. Interchanging prismatic structures are found for all ions, the main coordination number being 9, in good agreement with EXAFS experimental data. The ligand dynamics are characterized by first-shell mean residence times in the range of 50 to ∼200 ps and by force constants for the Ln(III)–O(water) bond between 75 and 100 Nm −1 .

Hydration properties of trivalent thulium and ytterbium ions in aqueous solution are investigated via quantum mechanical charge field molecular dynamics (QMCF-MD) simulations. The QMCF-MD formalism is a special type of QM/MM simulation, where the chemically most relevant part of the system – in this case the ion with its first and second hydration shells – is treated by quantum mechanics. The mean ion O distances and the average coordination numbers of the first hydration shells are compared with experimental EXAFS data. Mean ligand residence times, vibrational frequencies and force constants were evaluated to characterise the dynamics of the systems.

A theoretical study of dysprosium(III) and holmium(III) in aqueous solution based on a quantum mechanical charge field-molecular dynamics (QMCF-MD) simulation is presented. The obtained structural and dynamical data were found to be in good agreement with several experimental and theoretical data. It is shown that the coordination number is constantly switching between eight and nine adopting square antiprismatic and tricapped trigonal prismatic configurations, thus supporting the interpretation of experimental data.

A comparison of the hydration characteristics of di- and trivalent europium ions in aqueous solution is presented. The established quantum mechanical charge-field molecular dynamics (QMCF-MD) approach yielded two 30 ps simulations. Significant differences among the two species were found in the Eu–O radial distribution functions, both in good agreement with experiments. The first shell coordination numbers of 8.1 and 8.9 were observed for Eu(II) and Eu(III), respectively. The mean residence time of first shell ligands differ by more than one order of magnitude, the divalent ion's hydration shell being more flexible, which is underlined by a weak ion-water bond strength.