In principle, the 𝜌̅ used by aNCI can be generated from the ρ pro of each frame of the MD simulation based on classical force fields or the accurate density of each frame in an ab-initio MD simulation. Since the latter is very time-consuming, aNCI is typically used in combination with forcefield-based MD simulations. More technical details about aNCI, as well as guidance on how to prepare an appropriate MD trajectory for the analysis, can be found in our recent review. Here we will not introduce the aNCI analysis in more detail or give examples, because aNCI has several notable shortcomings in practical applications: (1) It requires a relatively fine grid quality; otherwise, the image will be noticeably jagged, much like the NCI map. (2) It may fail to display certain interactions in some systems and sometimes generates isosurfaces that are difficult to interpret meaningfully. (3) A large number of noisy isosurfaces often appear in regions of no interest, so a proper grid data screening process is almost always necessary to obtain an acceptable aNCI map. However, this screening is not only cumbersome but also somewhat arbitrary.