Madrid-2019 force field: An extension to divalent cations Sr²⁺ and Ba²⁺

In this work, we present a parameterization of Sr²⁺ and Ba²⁺ cations, which expands the alkali earth set of cations of the Madrid-2019 force field. We have tested the model against the experimental densities of eight different salts, namely, SrCl₂, SrBr₂, SrI₂, Sr(NO₃)₂, BaCl₂, BaBr₂, BaI₂, and Ba(NO₃)₂. The force field is able to reproduce the experimental densities of all these salts up to their solubility limit. Furthermore, we have computed the viscosities for two selected salts, finding that the experimental values are overestimated, but the predictions are still reasonable. Finally, the structural properties for all the salts have been calculated with this model and align remarkably well with experimental observations.