A many-body energy decomposition analysis (MB-EDA) scheme based on a target state optimization self-consistent field...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Interactions

Background:

• Understanding intermolecular forces in molecular clusters is crucial for various chemical and physical processes.
• Traditional methods often struggle to accurately capture complex many-body effects in condensed phases.

Purpose of the Study:

• To develop and validate a Many-Body Energy Decomposition Analysis (MB-EDA) method for studying cooperative and anti-cooperative effects in molecular clusters.
• To provide a quantum chemical tool for analyzing intermolecular interactions at a detailed level.

Main Methods:

• Combining Energy Decomposition Analysis (EDA) with Many-Body Expansion (MBE).
• Utilizing the Target State Optimization Self-Consistent Field (TSO-SCF) method.
• Decomposing intermolecular interaction energy into electrostatic, exchange, polarization, charge transfer, and dispersion terms.

Main Results:

• MB-EDA successfully decomposes interaction energies within the MBE framework.
• Electrostatic, exchange, and dispersion interactions are largely pairwise additive across studied systems.
• Many-body effects are significant and varied in polarization and charge transfer interactions for water and ionic liquid clusters.
• Acetonitrile-methane clusters exhibit minimal many-body effects due to the absence of strong directional interactions.

Conclusions:

• The MB-EDA method offers a robust approach to dissecting many-body effects in molecular aggregates.
• The study elucidates the distinct contributions of various interaction types to cooperative and anti-cooperative phenomena.
• MB-EDA is implemented in Qbics, providing a valuable tool for quantum chemical investigations of molecular systems.