Computational searches for crystal structures of dioxides of group 14 elements (CO, SiO, GeO) under ultrahigh pressure.

In this study, we focused on the effect of pressure on the crystal structures of dioxides of group 14 elements, SiO, GeO, and CO. Systematic searches for their crystal structures using the artificial force induced reaction method generated 219 and 147, 102 and 63, and 148 and 76 structures for SiO, GeO, and CO, respectively, at 1 and 10 atm. At 1 atm, cristobalite-like, quartz, anatase-like, and stishovite were stable structures for SiO and GeO. At 10 atm, structures of stishovite and CaCl type were relatively stable for SiO and GeO. At 1 atm of CO, molecular crystals were the most stable, whereas, quartz-like and cristobalite-like structures were obtained as stable structures at 10 atm. We discuss these pressure dependent structural variations systematically using the obtained structural dataset.