According to density functional theory (DFT), the information contained in the electron density should suffice to determine any molecular property in the ground state. To most people, however, DFT is merely a computational approach. It was Robert G. Parr, my Ph.D. advisor, who pioneered the effort to appreciate and quantify molecular structure, bonding, and reactivity properties in DFT language. The theoretical framework that he established is called Conceptual DFT, where electronegativity, hardness/softness, and Fukui function can be rigorously formulated, as outlined in his book with Weitao in 1989 and reviewed by myself in 2009.
Our new approach is different. We propose to employ simple density functionals such as Shannon entropy, Fisher information, Pauli energy, etc., for the purpose. Recent examples of our work include applying them to quantify
- Steric effect, steric charge, and stereoselectivity,
- Strong covalent interactions,
- Electrophilic/nucleophilic regioselectivity,
- Cooperativity, frustration, and homochirality.