Understanding the structure and electronic properties of Th 4+ -water complexes

We present a systematic quantum chemistry study of the [Th(H 2 O) n ] 4+ (n = 1 to 10) complexes to gain insight into their electronic structure and properties: the effect of the ligand distribution on the valence shells of the thorium(IV) ion is studied by means of the electron localization function (ELF) topological analysis. Particular care is given to the study of the mono-aqua complex both at its equilibrium geometry, using various tools such as energy decomposition analyses (EDA), and along its dissociation pathway. Indeed, as several electronic states cross the Th 4 + -H 2 O 0 ground state along the minimum energy path, we demonstrate that the diabatic representation implemented in MOLPRO is able to generate reference potential energy surfaces that will lead to the evaluation of diabatic dissociation curves. The calculated diabatic interaction energy curve will allow for a consistent parameterization of new generation force fields dedicated to heavy metals based on quantum chemistry.