A recent AIMD study allowed the calculation of the phase diagram of CO 2 under Earth mantle conditions (Figure ). It was found that, below 40 GPa, temperatures above 2000 K are required to make Reproduced with permission from Moog et al., Copyright 2021, American Chemical Society. the liquid reactive. At higher pressure, a polymeric fluid was observed. A related SiO 2 -like phase was predicted using AIMD early on. Dispersion-corrected DFT using PBCs yielded information on the structure and stability of molecular and non-molecular modifications of CO 2 at high pressure. Simple boron compounds have been modeled under pressure as well, due to the element's intriguing electronic properties and the ability of a boron atom to form one additional bond. Metadynamics simulations with a supercell of eight BI 3 molecules have yielded a new crystal phase containing dimers of BI 3 with approximate D 2h symmetry. The calculated decrease in volume due to the phase transition agrees with experiments. In DFT studies using PBCs, the oligomerization and eventual polymerization of the diborane (B 2 H 6 ) system has been discussed, along with a possible metallization if the pressure is high enough. Moreover, the possibility of unidirectional polymerization of some compounds under pressure has been demonstrated. Consecutive cycloaddition reactions lead to the formation of nanothreads, a futuristic class of one-dimensional polymeric materials valued for their superior mechanical performance. Calculations on the pressure-induced synthesis of nanothreads have been performed, e.g., with XP-PCM. The findings of this study are largely in line with those obtained for singular Diels-Alder reactions in that increasing pressure leads to a decrease in volume and activation energy barrier of the cycloadditions. The field of nanothread research, in particular investigations into novel synthetic pathways and the mechanical properties of the materials, will surely continue to grow. It will be exciting to see the crucial contributions made by computational tools in these research endeavors.