Density-Functional Theory with Dispersion-Correcting Potentials for Methane: Bridging the Efficiency and Accuracy Gap...

Area of Science:

• Computational Chemistry
• Molecular Modeling
• Physical Chemistry

Background:

• Classical mechanics simulations are essential for large molecular clusters but require accurate force-field parameters for noncovalent interactions.
• High-level correlated wave function methods (e.g., CCSD(T)) provide accurate data but are computationally expensive for parameter development.
• A computational gap exists between highly accurate but costly quantum methods and efficient but less accurate classical methods.

Purpose of the Study:

• To develop an efficient computational approach for generating accurate Lennard-Jones force-field parameters for noncovalent interactions.
• To bridge the accuracy and computational efficiency gap between high-level correlated methods and classical molecular mechanics.
• To demonstrate the efficacy of the proposed method using methane clusters.

Main Methods:

• Developed an intermediate computational step using PBE0-DCP (density-functional with dispersion-correcting potentials) and a 6-31+G(d,p) basis set.
• Utilized CCSD(T)-level binding energy data for small methane clusters to inform parameter development.
• Computed interaction forces for optimizing Lennard-Jones parameters by simulating methane molecule removal from a cluster.
• Validated Lennard-Jones parameters against dispersion-corrected density-functional calculations for methane clusters (2-40 molecules).

Main Results:

• Successfully developed methane-specific, atom-centered dispersion-correcting potentials (DCPs).
• Optimized Lennard-Jones parameters that closely reproduce dispersion-corrected density-functional calculation results when combined with CHARMM intramolecular parameters.
• Demonstrated the method's ability to accurately model binding energies in methane clusters of varying sizes.

Conclusions:

• The proposed intermediate computational approach effectively generates accurate Lennard-Jones force-field parameters for noncovalent interactions.
• This method provides a viable strategy to improve the accuracy of classical molecular mechanics simulations for molecular clusters.
• The outlined approach is generalizable for developing Lennard-Jones parameters for diverse molecular systems.