Atomic decomposition of Kohn–Sham molecular energies: the kinetic energy component

ABSTRACT

The decomposition of molecular energies into atomic contributions within Bader's atoms-in-molecules theory is instrumental in rationalising and accounting for not only the stability but also the reactivity of chemical species. Regardless of how it is achieved, it requires the partitioning of the electronic kinetic energy. While this is ‘natural’ (but computationally expensive) in the context of wavefunction approaches, it is not more practically straightforward in the framework of Kohn–Sham density functional theory, since the corresponding atomic fictitious (related to the non-interacting system) and correlation components must be calculated. In this paper, we discuss the ability of various approaches, based on either exact formal relationships or previously proposed functional approximations, to estimate them in an efficient way for a wide variety of molecular systems. Such results might pave the way toward the realistic modelling of larger systems of chemical interest and may provide new atomic descriptors to characterise atom types.

GRAPHICAL ABSTRACT

KEYWORDS:

• Bader's atoms-in-molecules theory
• Kohn–Sham DFT
• kinetic energy
• correlation energy
• approximate density functionals

Acknowledgments

The authors gratefully acknowledge the CRIHAN centre for providing computational resources.

It is our pleasure to dedicate this paper to our colleague Andreas Savin whose contributions to quantum chemical topology and DFT have always been an inspiration.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Centre National de la Recherche Scientifique (CNRS) for a “Chaire d'Excellence” at the University of Rouen, the LABEX SynOrg.