Global Search for Structures of Carbon Crystal Under Ultrahigh Pressure

In this study, a systematic search for structures of carbon crystal under ultrahigh pressure was performed by using the artificial force induced reaction method including periodic boundary conditions (PBC/SC-AFIR). To perform a search under an arbitrary pressure, an algorithm to take account of pressure was implemented in the GRRM program. At 100 GPa, the search generated 710 unique structures automatically. These structures were compared with 982 structures obtained by the search under zero pressure. The structures at 100 GPa were much denser than those under zero pressure. Besides, new structures that were denser than diamond were obtained at 100 GPa.