Stability of Solid Oxygen at High Pressure

Despite extensive theoretical and experimental studies, the stability of solid oxygen at high pressure remains an open question. Recent experimental results proposed a new phase that is stable at finite temperature [1]; however, the evidence is not conclusive. In this work, we reexamine the stability of the phase diagram of solid oxygen up to 100 GPa. In particular, we focus on the mechanical and thermodynamic stability of the recently proposed finite temperature phase. The influence of exchange interactions and the role of ion dynamics, including quantum effects, will be discussed.\\[4pt] [1] Alexander F. Goncharov, et al. \textbf{135}, 084512 (2011).