This work is assigned to study the influence of different interaction potential forms
on the pressure and internal energy of crystalline argon along its isothermal curves at high
temperatures, expanded from melting point temperature up to room temp
erature at
different molar volume values expanded up to its value, corresponded experimental
equilibrium curves with gaseous and liquid phases within the framework of quasi-classical
approximation. The pair-wise inter-atomic forces in conjunction with three-body forces
were taken into consideration. The results of this study regarding the pressure and internal
energy of crystalline Argon were compared with available experimental data. The
comparison clearly indicates that the calculated results coincide well with the experimental
results.