Equation of state and second critical point of highly compressed nitrogen

New model equation of state (EOS) for highly compressed polymerizing fluid is developed and calibrated on ab initio simulation data. The EOS was applied to the prediction of the fluid–fluid transition in strongly compressed nitrogen. Location of the fluid–fluid phase transition line and position of the critical point on it were estimated and compared with earlier predictions and experimental shock compression data.

► New improved EOS for polymerizing nitrogen fluid is developed.
► Estimated fluid-fluid critical temperature TC = 4890 K and pressure PC = 70.8 GPa.
► Polymerization is a general property of strongly compressed molecular fluids.