An efficient and accurate model for water with an improved non-bonded potential

Area of Science:

• Computational chemistry
• Molecular modeling
• Physical chemistry

Background:

• Standard molecular mechanical models for liquid water often use the Lennard-Jones potential, which may not accurately capture repulsion and dispersion interactions.
• Accurate modeling of water is crucial for understanding various chemical and biological processes.

Purpose of the Study:

• To develop a new molecular mechanical model for liquid water with improved representation of Pauli repulsion and dispersion interactions.
• To parameterize the model to accurately reproduce experimental physical properties of water.

Main Methods:

• Developed a TIP4P-type model with three atomic sites and a virtual site.
• Employed a Buckingham-type potential for Pauli repulsion and C6/C8 terms for dispersion interactions.
• Utilized the ForceBalance code for automated parameterization against experimental data.

Main Results:

• The developed model accurately reproduces experimental density, dielectric constant, enthalpy of vaporization, isothermal compressibility, thermal expansion coefficient, diffusion coefficient, and radial distribution function.
• The model incorporates a higher-order C8 dispersion term, often neglected in other force fields.
• An efficient, GPU-accelerated implementation is available in OpenMM using CustomNonBondedForce.

Conclusions:

• The new molecular mechanical model provides a more rigorous treatment of repulsion and dispersion interactions for liquid water.
• This approach offers a rational strategy for developing new force fields without significant code modifications or increased computational cost.
• The model's accuracy in reproducing experimental properties validates its utility for molecular simulations.