Fig. 6. (a) PBE-D2 crystal energy landscape for potential carbon dioxide crystal structures at 11.8 GPa with Z = 2 or 4 molecules in the unit cell. (b) Comparison for simulated powder X-ray diffraction patterns for the lowest-lying PBE-D2 predicted structures against the actual1 (purple) and simulated experimental phase III (using the purported structure) ones. Aside from the purported phase III structure, only the phase VII structure plausibly corresponds to the experimental data. Simulated diffraction patterns for all 25 low-energy structures are provided in ESI Section S6.† .
