Optimizing Noble Gas-Water Interactions via Monte Carlo Simulations

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• Standard Lorentz-Berthelot mixing rules inaccurately model noble gas-water interactions.
• This inaccuracy leads to significant deviations in simulated Henry's coefficients from experimental values.
• The potential well term (εij) is crucial for accurately representing noble gas-water interactions.

Purpose of the Study:

• To develop optimized noble gas-water Lennard-Jones 6-12 pair potentials.
• To improve the accuracy of simulated Henry's coefficients for noble gases in water.
• To provide reliable interaction potentials for modeling multiphase geological systems.

Main Methods:

• Optimized noble gas-water Lennard-Jones 6-12 pair potentials were developed for each noble gas.
• The εij term was scaled for helium, neon, argon, and krypton to match experimental Henry's coefficients.
• No scaling was applied to xenon due to its sensitive εij term and initial reasonable agreement.

Main Results:

• Optimized potentials significantly improved agreement with experimental Henry's coefficients for helium, neon, argon, and krypton.
• The developed potentials accurately predicted partitioning in CO2-H2O binary systems.
• Accurate diffusion coefficients in ambient water were also predicted using the optimized potentials.

Conclusions:

• The optimized pair potentials provide a robust foundation for future molecular modeling of multiphase geological systems.
• Adjusting the εij term is critical for accurate simulation of noble gas-water interactions.
• The validated potentials enhance the reliability of computational studies in geochemistry and materials science.