Probing non-covalent interactions with a second generation energy decomposition analysis using absolutely localized...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Energy Decomposition Analysis (EDA) is crucial for interpreting molecular interactions.
• Existing EDAs face challenges in defining terms when fragment electron densities overlap.
• Unique definitions are often impossible in chemically relevant overlapping regimes.

Purpose of the Study:

• To present an improved energy decomposition analysis (EDA) for Kohn-Sham density functional theory (DFT).
• To develop an EDA that is variational and uses valid antisymmetric electronic wavefunctions.
• To achieve simultaneous, previously unattainable properties in EDA.

Main Methods:

• Building upon the absolutely localized molecular orbital (ALMO)-EDA framework.
• Developing a second-generation ALMO-EDA.
• Ensuring all five interaction energy contributions have non-trivial complete basis set limits.

Main Results:

• The improved EDA is variational and employs valid antisymmetric electronic wavefunctions.
• It successfully calculates five key contributions: permanent and induced electrostatics, Pauli repulsions, dispersion, and charge transfer.
• All contributions exhibit non-trivial complete basis set limits.

Conclusions:

• The developed second-generation ALMO-EDA offers a more robust and accurate method for analyzing molecular interactions.
• This approach provides chemically interpretable contributions to interaction energy, even in overlapping density regimes.
• The method's applicability is demonstrated across various molecular systems, including dimers and a ter-molecular complex.