Thomas-Fermi model yields condensed phase of molecular metallic oxygen
  Calculations, performed in Thomas-Fermi approximation, show that the energy of a condensed phase of molecular metallic oxygen is lower by 496 kJ/mol than that of an insulator oxygen phase. The insulator phase is separated from a metallic one by energetic barrier of 1165 kJ/mol. This barrier could be overcome by means of electromagnetic irradiation with quantum energy of 12.071 eV or a bit higher. During such a transition the amount of energy equal to 496 kJ/mol is released. It should be extracted from a sample to secure the existence of a metallic phase. 
Yuri Kornyushin