From Density Functional Theory to Conceptual Density Functional Theory and Biosystems.

Area of Science:

• Computational Chemistry
• Theoretical Chemistry
• Quantum Chemistry

Background:

• Density functional theory (DFT) has evolved significantly since its inception.
• Conceptual density functional theory (CDFT) emerged as a key development within DFT.
• Various DFT descriptors quantify intrinsic chemical reactivity.

Purpose of the Study:

• To outline the historical development and position of CDFT within DFT.
• To chronologically present the introduction and characterization of DFT descriptors.
• To illustrate the broad applicability and future potential of CDFT.

Main Methods:

• Historical review of DFT and CDFT evolution.
• Perturbational approach to characterize DFT descriptors as response functions.
• Analysis of derived descriptors like electrophilicity and generalized philicity.

Main Results:

• All major DFT descriptors (electronegativity, hardness, Fukui function, etc.) can be viewed as response functions.
• These descriptors are applicable within established chemical principles (e.g., HSAB, maximum hardness).
• CDFT applications have expanded to encompass organic, inorganic, polymer, materials chemistry, catalysis, nanotechnology, and biosystems.

Conclusions:

• CDFT descriptors offer a powerful framework for understanding chemical reactivity.
• Methodological, software, and hardware advancements facilitate the study of larger systems, including biosystems.
• The continued evolution of CDFT promises further significant contributions to chemical sciences.