Charge density and chemical reactions: A unified view from conceptual DFT

Abstract

Conceptual density-functional theory (DFT) provides a mathematical framework for using changes of the electron density to understand chemical reactions and chemical reactivity. The key idea is that by studying the response of a molecule or materials to perturbations, one can decipher its reactivity preferences. If a system reacts favorably to a perturbation, then this indicates that the system will react favorably with a certain class of reagents. Differentials of the energy may thus be interpreted as reactivity indicators. Because of the key role of energy differentials, the mathematical framework of conceptual DFT is similar to classical thermodynamics, with state functions, variational principles, and Legendre transforms. In this chapter we use this thermodynamic simile to present the mathematical underpinnings of conceptual DFT. Applications to systems of interest to organic, inorganic, and biological chemists are used to demonstrate how these abstract concepts may be applied to concrete chemical problems.