Effect of scaled ionic charges on the freezing point depression of aqueous CaCl2 solution

•Madrid-2019 force field exhibits predictive consistency with experimental measurements relative to OPLS-AA.•Under scaled ionic charges, the mobility and interaction of the ions are enhanced at the freezing point. We examine the performance of two force fields, OPLS-AA (Optimized Potentials for Liquid Simulations - All Atom) using full ionic charges, and Madrid-2019 using scaled ionic charges, in predicting the freezing point depression of aqueous CaCl2 solutions across concentrations ranging from 5 to 30 wt%. The direct coexistence method is employed to characterize the phase transformation mechanism. Our predictions corroborate that the Madrid-2019 force field exhibits predictive consistency with experimental measurements relative to OPLS-AA. The dissimilarities in the equilibrium properties, such as diffusion coefficients, hydration structures, and densities, underscore the advantages in the ion-water and ion-ion interaction mechanisms described by Madrid-2019 force field.