The process of an atom shifting from its original trivalent or tricoordinate (ground state) configuration through a planar formation and then returning to its initial geometric structure is what we call a pyramidal inversion. This fluxional process is an ideal example of dynamic stereoisomerism, a process where the arrangement of atoms changes without the formation or breakage of bonds. To understand this process better, we often refer to Linus Pauling's hybridization concept. The original molecule configuration (C3v) shifts to a planar configuration (D3h) during the transition state (TS). This process can be described by a sequence of hybridization transitions: sp3 ⟶ sp2 ⟶ sp3 (see Scheme 1). It is well known that the activation barrier () a E for the 15 group elements highly depends on the inversion center. The umbrella inversion of ammonia is almost barrierless, demanding only 5.8-5.9 kcal/mol at room temperature (T = 298 K). Similar spectroscopic approaches estimate significantly higher a E for phosphine (PH3) and arsine (AsH3): 17.1 and 32.1 kcal/mol, respectively. Indeed, a higher value of 31.6 kcal/mol has also been reported for PH3. Predicted activation enthalpies  ‡ ( ), H calculated in the gas phase using range-separated corrected global-hybrid DFT functionals match closely with the experimental values. Any discrepancies range from 0.17 to 0.78 kcal/mol for ammonia, 7.36 to 10.93 kcal/mol for phosphine, and 3.71 to 7.82 kcal/mol for arsine. These consistent results across various systems suggest that the methodologies used are appropriate for examining the ELF topography along the IRC, yielding consistent results across various systems. Furthermore, these results indicate the analysis performed is independent on the computational method, aligning with recent observations. Please refer to the Electronic Supplementary Information (ESI) for additional details.