Development of an optimized intermolecular potential for sulfur dioxide

Area of Science:

• Physical Chemistry
• Chemical Physics
• Thermodynamics

Background:

• Accurate molecular models are crucial for predicting thermodynamic and transport properties of fluids.
• Sulfur dioxide (SO2) is an important industrial chemical, necessitating precise property predictions.

Purpose of the Study:

• To develop and validate a new, accurate force field for sulfur dioxide.
• To assess the performance of existing SO2 intermolecular potentials.

Main Methods:

• Development of a new intermolecular potential for SO2.
• Molecular simulations to calculate vapor-liquid equilibria, critical properties, and thermophysical properties.
• Comparison with experimental data and scattering experiments (neutron and X-ray).

Main Results:

• The new SO2 force field accurately reproduces experimental data for saturated liquid densities (within 0.5%), vapor pressures (within 2%), and heats of vaporization (within 2%).
• Predicted critical properties and normal boiling point show excellent agreement with experimental values.
• Calculated pair distribution functions (S-S, S-O, O-O) closely match neutron and X-ray scattering data.

Conclusions:

• The developed force field provides a significant improvement for predicting SO2 properties across various conditions.
• Existing SO2 models show limitations, particularly at temperatures deviating from their parametrization points.
• Molecular structure is only subtly influenced by variations in force field parameters.