Multiple pathways in pressure-induced phase transition of coesite

Significance Coesite is an important geological mineral, yet it presents complicated phase transformations under compression. Earlier reports of pressure-induced amorphization have been later refined showing formation of various crystalline structures, including a high-pressure octahedral phase. Due to the complicated structure nature of coesite, we need to represent the system in a relatively large box. Previous first-principles calculations are limited, as only a small unit cell was employed. Here, we carried out molecular dynamics simulations based on an ab initio parameterized polarizable force field. This approach allows us accurate simulations with relatively large system sizes, which eventually enables us to provide a theoretical identification of multiple transformation pathways that have been discovered so far.