Chemical Bonding in Physical Space

The goal is the complete chemical characterization of the electronic structure of a chemical system on the basis of the first-order (1-RDM) and second-order reduced density matrix (2-RDM) in position and momentum space.

This research includes several tasks/challenges:

• Development of chemical bonding (ChemBond) indicators in position and momentum space based on 1- and 2-RDM.
• Extraction of ChemBond information from experimentally accessible quantities, e.g., the electron density.
• Concrete analysis of  ChemBond situations in molecules and solids. Complete characterization of  ChemBond situations on the basis of physical space ChemBond indicators.
• Recovering and reformulating known ChemBond concepts from other conceptual frameworks, e.g., the Hilbert space of wavefunctions.
• Refining and extending known, and establishing new ChemBond concepts on the basis of physical space ChemBond indicators.
• Understanding and predicting chemical and physical properties on the basis of the ChemBond model developed.

Currently used concepts for position space analysis:

• The QTAIM (Quantum Theory of Atoms in Molecules) partitioning of position space: based on the electron density.
• Localization of electrons in, and delocalization between basins (localization and delocalization index) of variable type: based on the pair density.
• Localizability of an electron around a certain position (electron localizability indicator, ELI): based on the pair density. 
• Interacting Quantum Atoms (IQA) Approach: based on 2-RDM.