Chemical Accuracy in Modeling Halide Ion Hydration from Many-Body Representations

Despite the key role that ionic solutions play in several natural and industrial processes, a unified, molecular-level understanding of how ions affect the structure and dynamics of water across different phases remains elusive. In this context, computer simulations can provide new insights that are difficult, if not impossible, to obtain by other means. However, the predictive power of a computer simulation directly depends on the level of “realism” that is used to represent the underlying molecular interactions. Here, we report a systematic analysis of many-body effects in halide-water clusters and demonstrate that the recently developed MB-nrg full-dimensional many-body potential energy functions achieve high accuracy by quantitatively reproducing the individual terms of the many-body expansion of the interaction energy, thus opening the door to realistic computer simulations of ionic solutions.