On Atoms-in-Molecules Energies from Kohn-Sham Calculations

Herein, we discuss three methods to partition the total molecular energy into additive atomic contributions within the framework of Bader's atoms-in-molecules theory and in the particular context of Kohn-Sham density functional theory. The first method is derived from the virial theorem, whereas the two other schemes, termed "standard" and "model", are based on Pendás' interacting-quantum-atoms decomposition. The methods are then compared for a dataset of molecules of interest for direct application in organic chemistry and biochemistry. Finally, the relevance of the three methods for the prediction of intrinsic reactivity properties (e.g., electrophilicity) or for unravelling the nature of chemical bonding (e.g., in halogen bonds, beyond the pure electrostatic point of view), is examined and paves the way for their more systematic use for the in silico design of new reactants.