Solvation energies from atomic surface site interaction points.

Area of Science:

• Physical Chemistry
• Computational Chemistry

Background:

• Thermodynamic properties of fluids are crucial for chemical engineering processes.
• Existing models often struggle to accurately capture temperature-dependent behaviors.
• Non-covalent interactions play a significant role in molecular interactions within fluid phases.

Purpose of the Study:

• To generalize the Surface Site Interaction Model for Liquids at Equilibrium (SSIMPLE) for temperature-dependent calculations.
• To develop a model for fluid phase density based on intermolecular interactions.
• To assess SSIMPLE's ability to predict association constants and vapor-liquid equilibria across temperatures.

Main Methods:

• Generalized the SSIMPLE model to include temperature-dependent polar interactions.
• Developed an expansion energy concept based on net intermolecular Surface Site Interaction Point (SSIP) interactions.
• Utilized the atomic interaction point (AIP) version of SSIP for 171 compounds.
• Validated against experimental data for association constants and vapor-liquid equilibria (VLE) of binary mixtures.

Main Results:

• The non-polar interaction term in SSIMPLE is temperature-independent, while the polar term is temperature-dependent.
• The generalized SSIMPLE model accurately predicts the temperature dependence of association constants for H-bonded complexes.
• Calculated room temperature liquid densities using the AIP-SSIP description showed good agreement with experimental data.
• SSIMPLE successfully reproduced experimental vapor-liquid equilibria for 196 binary mixtures.

Conclusions:

• The generalized SSIMPLE model provides a robust framework for calculating temperature-dependent thermodynamic properties of fluids.
• SSIMPLE accurately models both liquid phase properties (density, association constants) and vapor-liquid equilibria.
• The model's ability to handle non-covalent interactions makes it versatile for various fluid systems.