Systematic Optimization of Water Models Using Liquid/Vapor Surface Tension Data

Area of Science:

• Computational chemistry
• Molecular dynamics simulations
• Physical chemistry

Background:

• Force field models are crucial for simulating molecular liquids.
• Heat of vaporization is a common experimental reference, but can be sensitive to corrections.
• Surface tension offers a less sensitive alternative for fitting force field parameters.

Purpose of the Study:

• To investigate surface tension as a replacement for heat of vaporization in fitting force field models.
• To develop a protocol for using surface tension in the ForceBalance optimization procedure.
• To revise parameters for TIP3P and TIP4P water models using surface tension data.

Main Methods:

• Utilized ForceBalance optimization procedure.
• Incorporated experimental surface tension measurements.
• Developed and tested revised TIP3P-ST and TIP4P-ST water models.

Main Results:

• The TIP3P-ST model accurately reproduced water's temperature of maximum density but showed overstructuring and less accurate transport properties.
• The TIP4P-ST model demonstrated high accuracy across various thermodynamic and kinetic properties.
• Surface tension proved a valuable fitting property, especially for liquids lacking quantum corrections.

Conclusions:

• Surface tension is a viable and useful experimental reference for fitting force field models.
• The TIP4P-ST model shows excellent performance, comparable to state-of-the-art models.
• This approach is particularly beneficial for molecular liquids where heat of vaporization corrections are challenging.