SELF-CONSISTENT INTEGRAL-EQUATION THEORY OF CHAIN-MOLECULAR LIQUIDS .2. IMPROVED INTERMOLECULAR EQUATIONS

Improved self-consistent intermolecular integral equations for a chain -molecular liquid are derived from the polymer Kirkwood hierarchy. The present work is a continuation of our recent work reported in a previ ous paper [J. Chem. Phys. 103, 2140 (1995)]. It is shown that the refe rence interaction site model (RISM) equation and extensions thereof ca n be obtained from the new intermolecular equations. The solutions of the new self-consistent set of intra- and intermolecular equations are compared with computer simulation data for chains with repulsive inte raction potentials whose lengths N vary from 4 to 100 sites. The inter molecular correlation functions obtained from simulations are accurate ly reproduced. Comparisons with simulation data for the pressure equat ion of state and excess chemical potential show that the predictions o f the self-consistent theory are accurate for packing fractions up to 0.4. These thermodynamic functions are found to scale as N for N > 16, implying that results obtained for short chains can be extrapolated t o much longer chains. (C) 1996 American Institute of Physics.