Group-15 elements. Experimental and theoretical data show that the pressure-induced A7to-Ah PT in As is characterized by the equalization of the three short primary intralayer, d1, and the three large secondary interlayer, d2, bond distances in As-I as pressure increases (Fig. ). Concomitantly, an equalizing trend is observed for ρd1 and ρd2 (Fig. ) and for ELFd1 and ELFd2 at BCPs (see Fig. in ESI). Remarkably, both ρ and ELF values for MMBs at Pt in As are smaller than those of covalent bonds at RP. Similar trends occur also in Sb and Bi during the A7-to-Ah PT and in Se and Te during the A8-to-Ai PT (see Fig. , S5, S8, and S10 in ESI). Furthermore, similar trends have also been reported in IV-VI and V2-VI3 compounds . Therefore, our results confirm that MMBs at Pt in group-15 and -16 elements are weaker than covalent bonds at RP, as already commented. In this context, it is worth noting that the covalent character previously attributed by many researchers to the MMBs in PCMs of the IV-VI family and Bi-III is likely due to the relatively high values of ρ and ELF found in MMBs, despite they are typically somewhat smaller than for covalent bonds (ρd1 and ELFd1).