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

We present an analysis of the thermodynamic properties of chain molecules formed from Yukawa segments using the statistical associating fluid theory with interactions of variable range (SAFT-VR) and the high-temperature expansion of the mean-spherical solution (MSA-HTE) to the Ornstein-Zernike equation for a simple Yukawa fluid. The SAFT-VR expressions derived previously for this system allow the MSA-HTE equation of state to be reformulated in terms of first-order perturbation quantities, thus improving its accuracy. Furthermore, the MSA-HTE solution provides a full theoretical derivation of the perturbation theory used in SAFT-VR, together with a completely analytical equation of state for chain molecules composed of segments which interact via the Yukawa potential. (C) 1999 American Institute of Physics. [S0021-9606(99)50242-0].