Assaying the nature of the chemical bond by visualizing and counting the electrons with negative energies

We propose here a new unbiased theoretical method to assay the nature of the chemical bond. It relies on the graphical representation of the local electron energy density H(r) and on the quantitative estimate of few associated analytical descriptors. The method self-consistently describes the chemical bond in terms of the three major categories typically used in the chemical language: the covalent bond, the ionic bond, and the non-covalent interactions driving the stability of more or less complex intermolecular aggregates. The large number of our explored species suggests that the proposed approach is of general validity and equally applicable to various types of chemical compounds. We, therefore, hope that it can find acceptance as an additional tool to investigate the peculiarities and fine properties of the chemical bond in nature.