Continuum polarizable force field within the Poisson-Boltzmann framework.

Area of Science:

• Computational Chemistry
• Molecular Modeling
• Physical Chemistry

Background:

• Accurate molecular modeling requires precise force fields.
• Continuum polarizable force fields offer a balance between accuracy and computational cost.
• Developing robust nonbonded parameters is crucial for force field performance.

Purpose of the Study:

• To develop and validate a new set of nonbonded parameters for a continuum polarizable force field.
• To assess the model's accuracy against quantum mechanics calculations and experimental data.
• To optimize and test atomic cavity radii for improved solvation energy predictions.

Main Methods:

• Development of nonbonded parameters for a continuum polarizable force field.
• Comparison of the model's electronic response and dipole moments with B3LYP/cc-pVTZ.
• Testing of Amber van der Waals parameter interchangeability between explicit and continuum models.
• Optimization of atomic cavity radii using experimental solvation free energies for 177 molecules.
• Validation of optimized radii against 176 independent test molecules using Poisson-Boltzmann calculations.

Main Results:

• The new continuum polarizable model demonstrates consistency with B3LYP/cc-pVTZ for electronic response and dipole moments.
• The model shows good agreement with MP2/cc-pVTZ for dimer binding energies (<0.9 kcal/mol deviation in aqueous dielectric).
• Optimized Poisson-Boltzmann atomic cavity radii exhibit excellent transferability, yielding an overall RMSD of 1.30 kcal/mol and an average unsigned error of 1.07 kcal/mol across 353 molecules.

Conclusions:

• The developed nonbonded parameters and optimized cavity radii provide a reliable continuum polarizable force field.
• The model's accuracy is comparable to high-level quantum mechanical methods for various molecular properties.
• This framework is suitable for constructing comprehensive protein and nucleic acid force fields.