Equation of state for fluids containing chainlike molecules

An equation of state for chain fluids has been derived through the r‐particle cavity‐correlation function (CCF) for chains obtained from sticky spheres; here r is the chain length. The r‐particle CCF is approximated by a product of effective two‐particle CCFs, accounting for nearest‐neighbor correlations and next‐to‐nearest‐neighbor correlations. For hard‐sphere chain fluids (HSCF), the density dependence for nearest‐neighbor effective two‐particle CCFs is determined by the equation of Tildesley–Streett for hard‐sphere dumbbells and that for next‐to‐nearest‐neighbor effective two‐particle CCFs by computer‐simulation results for hard‐sphere trimers. The final equation of state has a simple form which gives compressibility factors and second virial coefficients for homonuclear HSCFs covering a wide range of chain length (up to r=201) in excellent agreement with computer simulations. Satisfactory comparisons are also obtained between predicted and computer‐simulation results for homonuclear HSCF mixtures, HS...