Parameter Dependence of the Solubility Limit for Disodium Phosphate

Area of Science:

• Computational chemistry
• Physical chemistry
• Biophysics

Background:

• Accurate modeling of supersaturated solutions is crucial for understanding crystallization and phase behavior.
• Standard force fields often require parameterization for specific chemical systems.

Purpose of the Study:

• To calculate the solubility limit of disodium phosphate in water.
• To investigate the relationship between the sodium-oxygen Lennard-Jones radius parameter (Rmin) and solubility.
• To assess the transferability of adjusted parameters for modeling other systems.

Main Methods:

• Molecular dynamics simulations were used to calculate the solubility limit.
• The sodium-oxygen Rmin parameter in Lennard-Jones potentials was systematically varied.
• Simulations were performed using standard force fields, with minor adjustments to Rmin.

Main Results:

• A clear exponential relationship was observed between the sodium-oxygen Rmin and the solubility limit concentration.
• Small adjustments to Rmin successfully reproduced experimentally determined solubility limits.
• The same adjusted Rmin parameters accurately predicted both solubility limits and osmotic pressure.

Conclusions:

• The sodium-oxygen Rmin parameter is critical for accurately simulating disodium phosphate solubility.
• Adjusted Rmin parameters demonstrate transferability, enabling more precise modeling of phosphorylated proteins.
• This approach enhances the predictive power of computational models in physical chemistry and biophysics.