Accuracy limit of rigid 3-point water models

Area of Science:

• Computational chemistry
• Molecular modeling
• Physical chemistry

Background:

• Classical 3-point rigid water models are widely used for their computational efficiency.
• Existing models like TIP3P and SPCE have limitations in accurately reproducing water's properties.

Purpose of the Study:

• To develop a highly accurate 3-point rigid water model using a novel parameter optimization approach.
• To evaluate the performance of the new model against established models and experimental data.

Main Methods:

• Developed a new approach for constructing classical rigid water models, enabling exhaustive parameter searches.
• Applied this approach to create the Optimal Point Charge 3-point (OPC3) water model.
• Validated OPC3 against a comprehensive set of liquid bulk properties and charge hydration asymmetry.

Main Results:

• OPC3 demonstrates significantly higher accuracy than TIP3P and SPCE for bulk properties across various temperatures.
• OPC3 accurately predicts the charge hydration asymmetry of water, aligning closely with experimental results.
• Other recent models (TIP3PFB, H2ODC) show improved accuracy but do not surpass OPC3's performance.

Conclusions:

• The OPC3 model represents a significant advancement in the accuracy of 3-point rigid water models.
• The developed optimization method effectively identifies optimal parameters for electrostatic properties.
• The study suggests that current 3-point rigid non-polarizable models may have reached their practical accuracy limit.