Theoretical Study of Structures of Solid Oxygen under High Pressure

Abstract

The structure of solid oxygen under high pressure is studied up to 6 GPa with no empirical parameters. The potential of the crystal is described by superposition of O 2 pair potentials calculated by the ab initio method. Structural optimization is achieved with this potential energy surface. The monoclinic structure is stable up to 6 GPa and a monoclinic-orthorhombic structural transition is not found. The pressure dependence of lattice constants agrees with the result of recent X-ray diffraction experiments.