Improved general-purpose five-point model for water: TIP5P/2018.

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Materials Science

Background:

• Accurate molecular models are crucial for simulating liquid water properties.
• Existing models often struggle to simultaneously reproduce key thermodynamic and dynamic behaviors.
• Developing improved potentials requires careful charge derivation from ab initio calculations.

Purpose of the Study:

• To introduce TIP5P/2018, a refined five-point potential for liquid water.
• To derive atomic charges using ab initio per-molecule electrostatic potentials and split charge equilibration.
• To enhance the model's ability to reproduce target properties like density and diffusion dependence on temperature.

Main Methods:

• Development of the TIP5P/2018 water potential.
• Utilizing ab initio calculations for per-molecule electrostatic potentials in the liquid phase.
• Employing the split charge equilibration method by Nistor et al. (2006).

Main Results:

• Achieved significant improvements in the behavior of isothermal compressibility.
• Enhanced other thermodynamic and rotational properties of liquid water.
• The model exhibits a dipole moment close to ab initio values.

Conclusions:

• TIP5P/2018 offers improved accuracy for simulating liquid water compared to previous models.
• The charge assignment procedure leads to a quadrupole moment that is too small, overestimating the dielectric constant.
• Further refinement of charge derivation may be needed for precise dielectric property prediction.