The quantum mechanics-based polarizable force field for water simulations.

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Materials Science

Background:

• Accurate molecular simulations require reliable force fields for water.
• Existing water models often rely on empirical fitting, limiting their predictive power.
• Quantum mechanics (QM) offers a rigorous, data-driven approach to developing force fields.

Purpose of the Study:

• To develop a novel, accurate water force field based solely on quantum mechanics calculations.
• To validate the force field's performance against experimental data for solid and liquid water.
• To enable more accurate simulations of systems involving explicit water molecules.

Main Methods:

• High-level coupled cluster single double triple (CCSDT) QM calculations for water dimer.
• X3LYP density functional theory (DFT) for larger water clusters.
• Polarizable charge equilibration and DFT-D3 for nonbond interactions.

Main Results:

• The RexPoN force field shows excellent agreement with experimental data for water's solid and liquid phases.
• Key properties such as melting point, enthalpy, density, entropy, dielectric constant, and self-diffusion coefficient are accurately reproduced.
• The model demonstrates high fidelity across various orientations and distances in QM calculations.

Conclusions:

• RexPoN provides a highly accurate, QM-derived force field for water, eliminating the need for empirical data.
• This advancement is crucial for precise simulations in electrocatalysis, biomolecular systems, and materials science.
• The force field will enhance studies involving explicit water interactions in fuel cells, batteries, and drug discovery.