Metallization of liquid oxygen: singularity in its group

The insulator–metal transition in strongly compressed liquid oxygen observed at the density of 4.1 g/cm3 (Phys. Rev. Lett. 86 (2001) 3108) has been identified as percolation of overlapping classically accessible domains of electrons in molecules. The liquid structure is described within a model of hard spheres near the solidification point. The critical packing fraction has been determined by using an equation of state of virtual atoms with partially free valence electrons. The threshold fraction of the classically accessible volume has been found by using an invariant mean coordination number. The percolation conductivity caused by overbarrier hopping of electrons has been calculated and compared with experimental data.