Since IRI can display various interactions on an equal footing, it is ideal for revealing the variation in the strengths and types of interactions during structural changes. To illustrate this, Fig. presents an example of using IRI analysis for a complete SN2 reaction process. The supplementary material in Ref. also provides an IRI animation of this reaction process, which more intuitively shows the changes in the IRI isosurface. From the IRI maps of some representative structures in the reaction process shown in the figure, it can be observed that at the beginning of the reaction, the green region of the isosurface between OH -and CH3CH2Br indicates the formation of a weakly interacting complex. As the reaction progresses, the color of the isosurface between the O and C atoms becomes increasingly blue, clearly indicating that the attraction is strengthening. Eventually, an IRI isosurface with typical covalent bond characteristics is formed. Meanwhile, the C-Br bond that initially exists weakens gradually as the reaction continues, and by the end, only a large green isosurface remains between Br and C, reflecting the formation of a vdW complex between Br -and ethanol. This example demonstrates that using IRI analysis to study chemical processes is highly effective for understanding the reaction mechanism. Additional examples of applying IRI to explore chemical reactions can be found in our review and the original IRI paper. Figure IRI map of some representative structures in a SN 2 substitution reaction process.