Visualization of electron density changes along chemical reaction pathways

We propose a simple procedure for visualising the electron density changes (EDC) during chemical reaction, which is based on mapping of rectangular grid points stationary structure into (distorted) positions around atoms another structure. Specifically, small step along minimum energy pathway (MEP), displacement each point obtained as linear combination motion all atoms, with contribution from atom scaled by corresponding Hirshfeld weight. For several reactions (identity SN2, Claisen rearrangement, Diels-Alder [3+2] cycloaddition, and phenylethyl mercaptan attack pericosine A), our EDC plots showed an expected reduction densities severed bonds (or those bond-order lowered), opposite observed newly-formed or enhanced bonds. The were also shown copper triflate catalyzed N2O fragmentation, where N–O bond weakening initially occurred singlet surface, but continued triplet surface after reaching minimum-energy crossing (MECP) between two potential surfaces.