The dispersion interaction between quantum mechanics and effective fragment potential molecules

Area of Science:

• Computational chemistry
• Theoretical chemistry
• Molecular modeling

Background:

• Accurate calculation of intermolecular forces is crucial in molecular modeling.
• Existing methods for dispersion energy calculation between different modeling approaches can be computationally expensive.
• The general effective fragment potential (EFP2) method offers a computationally efficient alternative for modeling molecular systems.

Purpose of the Study:

• To develop a computationally efficient method for calculating dispersion energy between systems modeled by EFP2 and full quantum mechanics (QM).
• To enable accurate assessment of dispersion interactions in hybrid QM/EFP2 systems.

Main Methods:

• Calculation of C(6) dispersion coefficients using EFP2 dynamic polarizabilities and QM orbital information.
• Estimation of C(8) terms from C(6) terms for improved accuracy.
• Evaluation of two damping functions for the dispersion energy.
• Utilizing pre-computed terms from standard Hartree-Fock (HF) or EFP2 calculations.

Main Results:

• The proposed method accurately calculates dispersion energy between EFP2 and QM molecules.
• The method demonstrates significant speed improvements compared to traditional approaches.
• The inclusion of C(8) terms and damping functions enhances agreement with established methods like symmetry adapted perturbation theory.

Conclusions:

• The developed method provides a fast and accurate way to compute dispersion interactions in hybrid QM/EFP2 systems.
• This approach reduces the computational cost of modeling complex molecular interactions.
• The method is readily applicable within existing computational chemistry workflows.