Modelling phosphate hydration with a polarizable bond-dipole framework: parameter optimization and benchmark testing.

Area of Science:

• Computational Chemistry
• Molecular Modeling
• Physical Chemistry

Background:

• Accurate modeling of hydrated phosphate species is challenging due to polarization and many-body effects.
• The polarizable force field (PBFF) based on bond-centered dipoles has shown promise for molecular systems.
• Extending PBFF to phosphate-water interactions requires careful parameterization and validation.

Purpose of the Study:

• To extend the polarizable force field (PBFF) model to hydrated phosphate species.
• To accurately represent polarization and many-body effects in these systems.
• To provide a foundation for modeling phosphate-containing systems in condensed phases.

Main Methods:

• Parameterization of the PBFF model using high-level quantum mechanical reference data.
• Fitting included conformational energies, dipole moments of phosphate monomers, and interaction energies of phosphate-water dimers/trimers.
• Evaluation against DLPNO-CCSD(T)/CBS benchmarks.

Main Results:

• The adapted PBFF model achieved root-mean-square errors below 0.81 kcal mol⁻¹ for conformational energies and 2.06 kcal mol⁻¹ for many-body interaction energies.
• Dipole moments were reproduced with an error below 0.40 Debye.
• The model demonstrated reasonable accuracy in capturing key interaction patterns in small hydrated phosphate clusters.

Conclusions:

• The adapted PBFF model shows promise for simulating hydrated phosphate systems.
• It achieves comparable accuracy to existing polarizable models with fewer electrostatic parameters.
• Further development is needed for improved transferability and performance in condensed-phase environments.