Thermodynamic properties of He-H₂ fluid mixtures over a wide range of temperatures and pressures

The statistical mechanical perturbation theory was used to study the effect of pressure P and temperature T on the properties of mixing of helium-hydrogen fluid mixture. The short range repulsive potential was treated as the unperturbed reference system of the hard sphere mixture. The computed values of pressure agreed well with computer simulation results over an extended region of temperature (50K-4000K) and pressure (0.05 GPa-16 GPa). The results show that segregation, heterocoordination, or both may occur in the He-H₂ mixture depending upon its composition, temperature, and pressure.