Toward a Universal Water Model: First Principles Simulations from the Dimer to the Liquid Phase

Area of Science:

• Computational chemistry
• Physical chemistry
• Materials science

Background:

• Accurate modeling of water is crucial for understanding chemical and physical processes.
• Existing models often struggle to balance accuracy and computational cost.
• First-principles methods offer high accuracy but are computationally intensive.

Purpose of the Study:

• To introduce and validate a new full-dimensional, first-principles-derived model of water, HBB2-pol.
• To assess the model's performance across various water systems, from small clusters to the liquid phase.
• To provide a computationally efficient yet accurate model for water simulations.

Main Methods:

• Development of the HBB2-pol model using first-principles calculations.
• Application of the model in computer simulations of water dimers, small clusters, and liquid water.
• Comparison of simulation results with experimental data (virial coefficients, spectra) and high-level theoretical calculations.

Main Results:

• HBB2-pol accurately reproduces experimental second and third virial coefficients.
• The model correctly predicts the dimer vibration-rotation-tunneling spectrum.
• It accurately estimates relative energies of small water cluster isomers.
• When combined with quantum methods, HBB2-pol accurately describes liquid water structure and dynamics.

Conclusions:

• The HBB2-pol model offers a significant advancement in accurately simulating water across different phases.
• It provides a reliable tool for studying water's fundamental properties and behavior.
• This model bridges the gap between high-accuracy quantum methods and large-scale simulations.