Noteworthy, we consider that the three stages for group-15 elements show a parallelism with the molecular, semimolecular, and atomic/polymeric stages that have been evidenced but not fully explained in nitrogen and hydrogen at HP . As previously remarked, the pressure dependence of the intramolecular and intermolecular bond distances in N2 and H2 seems to show different stages between the pure covalent molecular stage and the HP metallic atomic stage. A deep analysis of these systems would require future calculations that are out of the scope of the present paper. In any case, the three-stage mechanism we propose for pnictogens seems to be consistent with the simulations of the (N2)3 system at HP carried out by Hoffmann and coworkers . They pointed out that there is a significant contraction of the intermolecular distance (contraction of van der Waals region between N2 molecules) and a corresponding negligible change of the intramolecular distance at low pressures (molecular regime, stage 1). This stage is followed by a pressure region in which there is an anomalous increase of the intramolecular distance once the intermolecular distance decreases below 1.6 Å (semimolecular regime, stage 2). Finally, a third pressure region was found where there is a normal contraction of both intramolecular and intermolecular bond distances once all single N-N bonds are formed (atomic/polymeric regime, stage 3). Interestingly, a similar behavior has been observed in hydrogen at HP . A normal decrease of both intramolecular and intermolecular H-H distances up to 100 GPa (stage 1) is followed by an anomalous increase (decrease) of the intramolecular (intermolecular) as pressure increases (stage 2), caused by the charge transfer from intramolecular to intermolecular bonds . The trans influence ends once both bond distances equalize and each bond has a single electron per atom pair, i.e., all H-H bonds are 2c-1e bonds (stage 3). This seems to be the case above 500 GPa once the atomic phases of hydrogen appear .