A cluster‐based extension of <scp>COSMO</scp> ‐ <scp>SAC</scp> for predicting <scp>VLE</scp> in inorganic salt solutions

Abstract This study extends the parameter set of the COSMO‐SAC model to inorganic salt‐containing solution systems for describing their vapor–liquid equilibrium (VLE) behavior. An equivalent modeling strategy is proposed in which inorganic salts form stable pseudo‐neutral clusters composed of cations, anions, and coordinated water molecules that effectively participate in VLE. Representative ion–solvent cluster structures are identified using molecular dynamics simulations and quantum chemical calculations and are incorporated into the COSMO‐SAC framework as independent components. Without introducing empirical fitting parameters, the extended model reasonably predicts the VLE behavior of dilute aqueous KNO 3 , NaNO 3 , and CaCl 2 solutions under atmospheric pressure. While deviations remain for strong electrolytes due to long‐range electrostatic interactions and complex solvation effects, this work demonstrates the feasibility of cluster‐based molecular thermodynamic modeling for electrolyte‐containing systems.