Recent Improvements to the NWChem COSMO Module.

Area of Science:

• Computational chemistry
• Quantum chemistry
• Theoretical chemistry

Background:

• The COSMO (COnductor-like Screening MOdel) solvation model is crucial for simulating chemical processes in solution.
• Accurate implementation of solvation models is essential for reliable computational chemistry predictions.
• Previous implementations may have limitations in cavity construction and surface charge handling.

Purpose of the Study:

• To present recent advancements in the COSMO solvation model implementation within the NWChem computational chemistry software.
• To introduce a novel cavity construction method based on the solvent-excluding surface (SES).
• To improve the accuracy and robustness of charge correction schemes in the COSMO model.

Main Methods:

• Implementation of a new cavity construction algorithm using the GEPOL method and solvent-excluding surface (SES).
• Development of a procedure to merge close surface segments, mitigating numerical artifacts.
• Review and enhancement of methods for correcting outlying surface charges.
• Computation of dielectric solvation energies for a diverse set of ~100 molecules.
• Comparison of NWChem results with GAMESS using the double-cavity method.

Main Results:

• The new NWChem implementation achieves excellent agreement with reference methods for dielectric solvation energies.
• Mean unsigned deviations of approximately 0.15 kcal/mol were obtained with simplified correction schemes.
• Predictions of vapor-liquid and liquid-liquid equilibria using a COSMO-SAC variant showed highly promising results.
• The improved methods effectively handle surface charge complexities and reduce numerical artifacts.

Conclusions:

• The enhanced COSMO implementation in NWChem provides accurate and reliable solvation energy predictions.
• Simplified correction schemes in NWChem can achieve high accuracy comparable to more complex methods.
• The advancements facilitate more precise simulations of chemical behavior in solution and phase equilibria.