Using Force Matching To Determine Reactive Force Fields for Water under Extreme Thermodynamic Conditions

Area of Science:

• Computational chemistry
• Materials science
• Physical chemistry

Background:

• Classical force fields are essential for molecular dynamics simulations.
• Simulating water under dissociative and superionic conditions presents significant challenges.
• Existing methods struggle to accurately capture the behavior of water under extreme thermodynamic states.

Purpose of the Study:

• To develop a novel method for generating classical reactive force fields for water.
• To accurately model water's behavior under dissociative and superionic conditions.
• To bridge the gap between quantum mechanical accuracy and classical simulation timescales.

Main Methods:

• Utilized force matching to molecular dynamics trajectories.
• Employed Kohn-Sham density functional theory (DFT) for high-accuracy reference data.
• Applied the method to liquid water under dissociative conditions and superionic water.

Main Results:

• The developed force fields accurately reproduced DFT-computed structural and dynamic properties.
• Molecular concentrations and lifetimes were well-reproduced by the new models.
• The method demonstrated success in modeling water under extreme conditions, including superionic states.

Conclusions:

• The force-matching approach offers a straightforward way to create accurate classical reactive force fields.
• This method retains much of the accuracy of DFT for specific thermodynamic states.
• The generated force fields enable simulations at experimental time and length scales.