An analytical equation of state for chain molecules formed from Yukawa segments

We present an analysis of the thermodynamic properties of chain molecules f ormed from Yukawa segments using the statistical associating fluid theory w ith interactions of variable range (SAFT-VR) and the high-temperature expan sion of the mean-spherical solution (MSA-HTE) to the Ornstein-Zernike equat ion for a simple Yukawa fluid. The SAFT-VR expressions derived previously f or this system allow the MSA-HTE equation of state to be reformulated in te rms of first-order perturbation quantities, thus improving its accuracy. Fu rthermore, the MSA-HTE solution provides a full theoretical derivation of t he perturbation theory used in SAFT-VR, together with a completely analytic al equation of state for chain molecules composed of segments which interac t via the Yukawa potential. (C) 1999 American Institute of Physics. [S0021- 9606(99)50242-0].