Electron Density Based Partitioning Scheme of Interaction Energies

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Accurate calculation of interaction energies is crucial for understanding molecular complexes.
• Existing methods often lack detailed breakdowns of repulsive forces.
• Deformation density analysis provides qualitative insights but lacks quantitative energy correlation.

Purpose of the Study:

• To introduce a new partitioning scheme for complex interaction energy.
• To enable a more detailed analysis of repulsive energy components.
• To bridge the gap between qualitative density analysis and quantitative energy calculations.

Main Methods:

• Decomposition of one-electron and exchange-correlation densities into unperturbed and deformation densities.
• Application of the partitioning scheme at Self-Consistent Field (SCF) and post-SCF levels.
• Comparison with results from symmetry-adapted perturbation theories.

Main Results:

• The new method successfully partitions interaction energy into electrostatic, exchange-repulsion, and polarization terms.
• Exchange-repulsion is further resolved into exchange and Pauli-repulsion energies.
• The method accurately reproduces first-order terms from perturbation theories.
• Quantitative interaction energy components are directly linked to qualitative deformation density plots.

Conclusions:

• The proposed energy partitioning offers a more detailed and intuitive understanding of molecular interactions.
• It provides a clear graphical interpretation of complex formation.
• This method enhances the analysis of repulsive forces in molecular systems.