Heterogeneous Intramolecular Electric Field as a Descriptor of Diels–Alder Reactivity

External electric fields have proven to be an effective tool in catalysis, on par with pressure and temperature, affecting the thermodynamics kinetics of a reaction. However, molecules are complicated heterogeneous vector objects, there is no universal recipe for grasping exact features these that implicate reactivity. Herein, we demonstrate topological field within reactant state quantum mechanical electron density—a scalar reporter experienced by system—can identified as rigorous descriptors reactivity follow. We scrutinize specifically Diels–Alder Its 3D nature lack singular directionality charge movement upon barrier crossing make effect not obvious. show topology around dienophile double bond associated changes density this predictors reaction barrier. They also metrics rationalize predict how external would inhibit or enhance The findings pave way toward designing catalysis reading without explicit mechanistic interrogation, variety reactions.