In this section, we perform a systematic theoretical study of the two families of p-type elements at HP, paying special attention to the effect of pressure on the distortion from the octahedral coordination in the trigonal R-3m and P3121 structures of group-15 (As, Sb, Bi) and -16 (Se, Te) elements at RP, respectively (Strukturberich types A7 and A8, respectively), as well as on the Pm-3m (sc) and R-3m structures of α-Po and β-Po at RP, respectively (Strukturberich types Ah and Ai, respectively). To check the goodness of our theoretical simulations, we have compared the pressure-induced, simulated changes in the structural and vibrational properties of the lowcoordinated A7 (As, Sb, Bi) and A8 (Se, Te) phases with available experimental results. The relatively good agreement with experimental results using the PBEsol functional allows us to extrapolate our results to the less well-known HP phases of these two elemental families.