Self-consistent fluid variational theory for the equation of state and dissociation of densehydrogen and nitrogen

Abstract

The self-consistent fluid variational theory (SFVT) is used to calculate thepressure dissociation of dense hydrogen and nitrogen at high temperatures.The accurate high-pressure and high-temperature effective pair potentials areadopted to describe the intermolecular interactions, which are made to considermolecular dissociation. This paper focuses on a mixture of atoms and moleculesand is devoted to the study of the phenomenon of pressure dissociation at finitetemperature. The equation of state and dissociation degree are calculated from thefree energy functions in the temperature range 4000–15 000 K and density range0.1–3.2 g cm−3 for dense nitrogen and in the temperature range 2000–10 000 K and density range0.02–1.0 g cm−3 for dense hydrogen, which can be compared with other approaches and experiments. Thepressure dissociation is found to occur in the higher density range, while temperaturedissociation is a more gradual effect.