The Ab Initio Understanding of Solid Oxygen: The Alpha and Delta Phases

We investigate the alpha–delta phase transitions of solid oxygen using spin-polarized density functional theory. We employ the nonlocal van der Waals functionals vdW-DF-cx scheme (Phys. Rev. B 2014, 89, 035412) to the alpha and delta phases. The results indicate the polymorphic structure of the alpha and delta phases and thus explain the inconsistencies of the experimental measurements.