Local structure of liquid oxygen up to supercritical conditions from ab initio pair potentials

The local structure and orientational correlations (OCs) of liquid oxygen up to supercritical conditions have been determined using highly accurate ab initio pair potentials and a spin-average approximation. The predicted radial distribution functions are in excellent agreement with all the available experimental data covering a wide range of temperatures and pressures. The elusive shoulder characteristic of several diatomic fluids is accurately reproduced and, more importantly, its true origin elucidated by performing an exhaustive analysis of the OCs, indicating the relevance of specific configurations.