Extended Conductor-like Polarizable Continuum Solvation Model (CPCM-X) for Semiempirical Methods.

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Physical Chemistry

Background:

• Accurate solvation free energy calculations are crucial for understanding chemical processes.
• Existing semiempirical quantum mechanics methods often lack sufficient accuracy for solvation effects.
• Polarizable continuum models (PCM) are widely used but can be computationally demanding or less accurate.

Purpose of the Study:

• To develop a novel, accurate, and computationally efficient method for calculating solvation free energies.
• To integrate a domain decomposition conductor-like screening model (ddCOSMO) into the extended tight binding (xTB) framework.
• To improve upon existing solvation models within the xTB program package.

Main Methods:

• Developed the extended conductor-like polarizable continuum model (CPCM-X) for xTB.
• Incorporated the computationally efficient domain decomposition conductor-like screening model (ddCOSMO).
• Utilized a post-processing approach referencing established solvation models (COSMO-RS, SMD).

Main Results:

• CPCM-X demonstrates high accuracy across various benchmarks, including hydration and non-aqueous free energies.
• Achieved up to 40% improvement in accuracy for supramolecular association reactions compared to current xTB methods.
• The new method matches the accuracy of higher-level DFT-based models (COSMO-RS, SMD) while being over 100 times faster.

Conclusions:

• The CPCM-X method provides a significant advancement in accurate and efficient solvation free energy calculations for xTB.
• This method is broadly applicable to neutral and charged species in various solvent environments.
• The developed model is readily available in the xTB program for diverse computational chemistry applications.