Analyzing Many-Body Charge Transfer Effects With the Fragment Molecular Orbital Method

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Accurate calculation of interaction energies is crucial in chemistry.
• Charge transfer (CT) is a key component of intermolecular interactions.
• Existing methods may not fully capture many-body effects in CT.

Purpose of the Study:

• To develop a many-body expansion for charge transfer (CT) energies.
• To apply this expansion within the fragment molecular orbital (FMO) method.
• To elucidate the role of CT in various molecular systems.

Main Methods:

• Developed a many-body expansion of CT energies.
• Integrated this expansion into the fragment molecular orbital method.
• Utilized frontier orbital diagrams for graphical illustration.
• Applied the method to analyze interactions in water clusters, solvated ions, and polypeptide motifs.

Main Results:

• Successfully decoupled charge transfer and mixed terms in interaction energy decomposition.
• Provided a detailed analysis of many-body charge transfer effects.
• Quantified the contribution of CT to molecular interactions in diverse systems.

Conclusions:

• The developed many-body expansion offers a robust framework for analyzing CT energies.
• This method enhances the understanding of molecular interactions by explicitly accounting for many-body CT effects.
• The approach is applicable to a range of chemical systems, from small clusters to biomolecular motifs.