Merging the Energy Decomposition Analysis with the Interacting Quantum Atoms Approach

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Chemical Physics

Background:

• Energy Decomposition Analysis (EDA) dissects interaction energy but requires reference states, limiting predictive models.
• Interacting Quantum Atoms (IQA) offers reference-free decomposition but has limited connection to heuristic chemical models.
• Previous efforts have not synergistically combined EDA and IQA methodologies.

Purpose of the Study:

• To present a novel synergistic combination of EDA and IQA, termed EDA-IQA, for analyzing intermolecular interactions.
• To apply EDA-IQA to diverse interaction types, including hydrogen bonding, charge-dipole, π-π, and halogen interactions.
• To provide a richer energy decomposition scheme bridging real-space and Hilbert-space methodologies.

Main Methods:

• Decomposition of individual terms from EDA using the Interacting Quantum Atoms (IQA) approach.
• Application of the EDA-IQA method to a diverse set of molecular systems with various intermolecular interactions.
• Analysis of intra- and inter-fragment contributions to electrostatic, Pauli repulsion, and orbital interaction terms.

Main Results:

• EDA-IQA reveals non-negligible intra-fragment contributions to EDA's electrostatic term due to charge penetration.
• The Pauli repulsion term is decomposed into destabilizing intra-fragment and stabilizing inter-fragment contributions.
• Orbital interaction terms show contributions driven by charge transfer and stabilization along dissociation paths.

Conclusions:

• EDA-IQA provides a more detailed energy decomposition, offering insights into charge penetration and Pauli repulsion effects.
• The methodology successfully bridges the gap between real-space (IQA) and Hilbert-space (EDA) approaches.
• EDA-IQA aids in identifying causal effects on molecular geometries and reactivity through directional partitioning.