A view of covalent and ionic bonding from Maximum Probability Domains

Connecting the accurate Quantum Mechanics to the chemical view is the first of foremost purposes of interpretative methods in general, and topological analysis in particular. In this field of methods, the Maximum Probability Domains (MPD) analysis, is conceptually appealing but has not been extensively applied yet. In this study we provide the general vision coming out from MPD on the two main family of bonds: polar-covalent and ionic bonds. An interesting picture arises concerning the MPD solution associated to covalent bonds, displaying a prolate shape that extends preferentially in the orthogonal direction to the bond axis, and not along it. The polarity of the bond only affects marginally the domain shape, though further probability analysis seems to allow quantifying it. Concerning the ionic bond, a resonating picture emerges, which is compatible, and refines, the usual electrostatic vision of two oppositely-charged atoms in interaction.