High-pressure structures and metallization of sodium chloride

Sodium chloride (NaCl) is known as salt and an ionic insulator at ambient conditions. The high-pressure structures of NaCl have been extensively explored through a particle swarm structural search at zero temperature and pressure range of 0-800GPa. In addition to the known low-pressure insulating phases, we find three novel orthorhombic high-pressure structures: oC8 (stable at 322-645GPa), oI8 (stable at 645-683GPa), and oP16 (stable at above 683GPa). The oC8 structure can be metallized via band-gap closure under high pressure, while both oI8 and oP16 are metallic in their stable pressure ranges. Intriguingly, our predicted metallic high-pressure phases of NaCl retain predominant ionic behaviors. The peculiar conductive behaviors can be attributed to the extended anion sublattice. Copyright (C) EPLA, 2012