The fundamental question of how intermolecular interactions lead to the stabilization of heavy halides (Br−, I−, At−) microsolvated with up to six explicit water molecules is addressed here. An exhaustive exploration of the potential energy surfaces using a random search algorithm followed by optimization of molecular geometries using pseudopotentials and at the full four component relativistic levels of theory, affords a good number of structures with high probabilities of occurrence, highlighting the important role of local minima to reproduce experimentally measured properties. Sequential hydration enthalpies for astatide are reported here for the first time in the scientific literature. Closed shell (ionic, long range) as well as intermediate character interactions (contributions from closed shell and covalent) are at play stabilizing the clusters. The ability of water molecules to either donate or to accept electron density dictates the nature and strength of the corresponding hydrogen bonds in solvation shells. Binding energies and molecular geometries are shown to be more sensitive to electron correlation than to relativistic effects.

An exhaustive exploration using non-relativistic and four-component relativistic formalisms of the potential energy surfaces for the microsolvation of Sr 2+ , Ba 2+ with up to n = 6 water molecules is presented in this work. A multitude of well defined local minima stabilized by cation Á Á Á water and by water Á Á Á water interactions are found.Cation Á Á Á water contacts transcend the electrostatic interactions of simplistic ionic bonding. The formal charge causes a chaotropic effect in the structure of the solvent affecting water to water hydrogen bonds and inducing water dissociation and microsolvation of the resulting H + , OH À ions in extreme cases. Relativistic effects are close to 0.7% or smaller in geometries and electronic energies, but they are around 27% for shieldings of Ba 2+ clusters. The nuclei of the central cations are deshielded (around 10% in going from n ¼ 1 to n ¼ 3) due to microsolvation.

Publisher's PDF, also known as Version of record document license Article 25fa Dutch Copyright Act Link to publication in VU Research Portal citation for published version (APA) NL-eEDM Collaboration (2022). Benchmarking of the Fock-space coupled-cluster method and uncertainty estimation: Magnetic hyperfine interaction in the excited state of BaF.