It is important to notice that all the aforementioned QCr works at HP were performed in the pressure regime < 20 GPa. Moving towards higher pressures, instead, Na2He is among the first examples where a newly discovered HPE has been studied using some of the tools of QCr . Synthesized at P > 113 GPa in a DAC after being computationally predicted, Na2He is both a neutral helium-based compound and a possible HPE, which was confirmed by the topological analysis of the theoretical electron density. In fact, non-nuclear maxima (NNM) were located at the center of the interstitial sites of Na2He, where the charge concentration was attributed to the formation of an 8-center two-electron (8c-2e) multicenter bond (MCB) between the surrounding eight sodium atoms. Similarly, the electride nature of Na-hP4 was elucidated using analogous quantum chemical topology methods . It was shown that the valence orbitals of Na undergo (s)pd-hybridization and that these new orbitals could constructively combine with these same orbitals from the other sodium atoms comprising the Na11 cages, characteristic of the Na-hP4 phase, to form a chemical bond.