Probing internal electric fields of π‐ and σ‐hole bonds

π‐ and σ‐holes are nonnuclear molecular regions of positive electric potential, which make non‐covalent interactions with negative sites, for example, lone pairs of molecules containing nitrogen or oxygen, the so called π‐ and σ‐hole bonds. We investigate these bonds locally using a probe programmed as a virtual molecule. Unlike the hydrogen bond, electric fields are detected having strengths that are different from the sum of the separated parts, meaning that molecular electrostatic potential surfaces analysis of the different parts are not enough to analyze the bonds. Based on an application of the Hellmann‐Feynman theorem, which states that intermolecular bonds are fully described by Coulombian interactions (electrostatic plus polarization), we connect the electric field strength with the bond strength measured in experiments, so that it can be considered as a quantifier for the bonds. σ‐ and π‐bonds are responsible for new kinds of stable non‐covalent assemblies of molecules. Like hydrogen bonds, they are assumed to be described by Coulombic interactions, without further quantum effects. In the present work, a fictitious isotopic probe is used to evaluate the electric field in the middle of the bonds. The electric field intensity is proposed as a quantifier for the bonds, in accordance with some experimental results.