A transferable classical potential for the water molecule.

Area of Science:

• Computational Chemistry
• Materials Science
• Physical Chemistry

Background:

• Accurate molecular modeling is crucial for understanding water's diverse properties.
• Existing classical models often struggle to capture the full phase diagram of water.

Purpose of the Study:

• To develop a novel, computationally efficient classical model for water.
• To validate the model's accuracy across a wide range of conditions, including gas clusters and high-pressure ice.

Main Methods:

• A three-Gaussian charge model for the water molecule was developed.
• Ewald summation techniques were employed to derive potential energy, forces, and pressure.
• Model parameters were fitted using gas-phase cluster data and experimental values.

Main Results:

• The model accurately reproduces the dipole and quadrupole moments of gas-phase water.
• It successfully predicts properties of water clusters, ambient water, hexagonal ice, and high-pressure ice VII.
• Calculations of pair-correlation functions, compressibility, heat capacity, and diffusion coefficients show excellent agreement with experimental data.

Conclusions:

• This new classical water model demonstrates remarkable accuracy across the entire phase diagram.
• It provides a robust tool for simulating water behavior from molecular clusters to extreme pressures.