This surface encloses a defined fraction of the total electron probability density of the molecule . Typically, MESP data is visualized by plotting it on a specific electron density isosurface. For example, Figure displays the computed MESP data of paracetamol on an electron density isosurface with a value of 0.004 au. MESP analysis utilizes color-coded contours on the isosurface to depict the variation in electrostatic potential at different points. Different colours represent varied MESP, with highly positive regions in red (e.g., carbonyl carbon and CH bond hydrogens) indicating electron deficiency, while negative MESP regions in blue (e.g., hydroxyl oxygen, carbonyl oxygen, and π-region of the aromatic ring) indicate electron-rich features. Moreover, by employing colour grading to represent positive, negative, and neutral electrostatic potential regions, MESP offers a visual approach to understanding the size, shape, and relative polarity of a molecule, providing valuable insights into its reactivity, hydrogen bonding, and structure-activity relationships MESP, a measurable reactivity index, is derived from electron density data using computational methods and experimental techniques such as X-ray diffraction analyses of crystals. When molecules approach for a reaction, their interaction is governed by Coulombic energy, the primary component of the overall interaction energy. This energy is vital for orienting molecules favourably before the reaction starts, marking the initial phase.