Abstract
A systematic computational approach to AnIII hydration on a density-functional level of theory, using quasi-relativistic 5f-in-core pseudopotentials and valence-only basis sets for the AnIII subsystems, is presented. Molecular structures, binding energies, hydration energies, and Gibbs free energies of hydration have been calculated for [AnIII(OH2)h]3+ (h = 7, 8, 9) and [AnIII(OH2)h−1·OH2]3+ (h = 8, 9), using large (7s6p5d2f1g)/[6s5p4d2f1g] AnIII and cc-pVQZ O and H basis sets within the COSMO implicit solvation model. AnIII preferred primary hydration numbers are found to be 8 for all AnIII at the gradient-corrected density-functional level of theory. Second-order Møller–Plesset perturbation theory predicts preferred primary hydration numbers of 9 and 8 for AcIII–MdIII and NoIII–LrIII, respectively.