Using interpolation for fast and accurate calculation of ion-ion interactions

Area of Science:

• Computational Chemistry
• Biomolecular Simulations
• Physical Chemistry

Background:

• Understanding ion interactions in aqueous solutions is crucial for biomolecular simulations.
• Molecular dynamics (MD) simulations are computationally intensive for calculating potentials of mean force (PMFs).

Purpose of the Study:

• To develop a computationally efficient method for calculating ion-pair potentials of mean force (PMFs).
• To enable rapid and accurate assessment of salt bridge strengths and bridging water effects in biomolecular systems.

Main Methods:

• Extensive molecular dynamics (MD) simulations of ion pairs (2-5.5 Å diameter, ±1 charge) in explicit water (TIP3P).
• Development and application of an interpolation scheme (i-PMF) for predicting PMFs.

Main Results:

• The i-PMF method accurately captures PMFs for various ion sizes, reducing computation from 100 hours to seconds per PMF.
• Simulation data aligns with Collins' "law of matching affinities" regarding ion solubility.
• Small-small and large-large ion pairs show poor solubility, while small-large pairs are highly soluble.

Conclusions:

• The i-PMF method offers a significant computational advantage for studying ion interactions in biomolecular simulations.
• The findings support and provide a computational framework for understanding ion solubility trends.