Density functional theory and Bader's atoms-in-molecules theory: towards a vivid dialogue

Density functional theory and Bader's atoms-in-molecules theory share the same primary ingredient: the electron density, which is the fundamental physical observable in quantum chemistry. In this paper, we elaborate on the decomposition of the Kohn-Sham molecular energy in terms of Bader's partition, discussing how Pendás' Interacting Quantum Atoms framework could be adapted to a DFT context. Besides, another bridge between these two theories is built through a general formalism able to generate new local descriptors from any second-order density gradient expansion. These approaches are then applied to two classes of intramolecular bonds: between two electronegative atoms and intramolecular hydrogen bonds, illustrating how fruitful a dialog between both theories can be.