Prediction of the structure factor behavior of mono atomic fluids using the HNC approximation and the ISM equation of state

In the present work, an analytical expression has been obtained for the direct correlation function (DCF). Derivation of this relation was based on the well known statistical mechanical relation between bulk modulus and DCF. Analytical expression of the bulk modulus has been derived using Ihm-Song-Mason (ISM) equation of state (EoS), and we have used the hyper netted chain (HNC) approximation for the DCF in terms of the density expansion. Applying the obtained DCF makes possible to have structure factor (SF) at any given thermodynamic state. We have calculated the SF in this way for liquid argon and compared the results of our calculations with the experimental data at different temperatures and densities and at almost entire range of the attractive and repulsive of inter atomic distances. The agreement between the calculated SF and the experimental data are qualitatively reasonable.