We will prove that unconventional MMBs, as those occurring in PCMs at RP, also occur in the Ah and Ai phases of Po at RP and of As, Sb, Bi, Se, and Te at HP. For that purpose, we calculate several quantum-mechanical bonding descriptors of physical and chemical meaning for the studied phases. In particular, we will use descriptors extensively used by Wuttig and coworkers and Manjón and coworkers , such as the optical phonon frequencies, ωi, and the corresponding Grüneisen parameter, γi, which can give evidence of soft bonds and lattice anharmonicity; the average of the diagonal components of the Born effective charge tensor, Z*, which accounts for the bond polarizability, and the ES and ET values, which allow understanding the degree of bond covalency and ionicity, respectively. We will also use other bonding descriptors used by Lee and Elliott, Dronkowski and coworkers, and Manjón and coworkers , such as ρ, ∇ 2 ρ at BCP, and the pCOHP, IpCOHP(2c), and ICOBI(3c) parameters. These last parameters will help us to describe the evolution of the different atomic interactions as pressure increases. All these parameters, previously used for binary and ternary PCMs, as already remarked, will show us how physical and chemical worlds can be made compatible to provide a richer perspective of the unconventional bonds present in the octahedrallycoordinated phases of pnictogens and chalcogens. More specifically, the existence of MMBs will be evidenced by the small ωi, soft-mode behavior, and large γi for optical phonons, the extremely high values of Z*, and the ES values close to 1. In addition, the existence of MMBs will be confirmed by: i) the very small value of ∇ 2 ρ , which is intermediate between the negative values, typical for the covalent bond, and the positive values, typical for the metallic bond ; and ii) a value of ICOBI(3c) different from zero, which gives account for the multicenter character of MMBs .