Hypemetted chain approximation reference

Kusalik PG, Patey GN The solution of the reference hypemetted-chain approximation for water-hke models. Mol Phys 65(5) 1105—1119, 1988. 

An extension of the HNC approach is the reference hypemetted chain (RHNC) approximation [52-54]. In this approach, studying a system preliminarily requires that we determine the properties of a reference fluid (RF). Usually, it has to be assumed that the properties of the actual system are closed to those of the RF. For example, the interaction potential of the system under study can be written as the sum of the RF potential and of a small perturbation, namely, u r) = wRF(r) + Au(r). Correspondingly, one has y(r) = yKF(r) + Ay(r), and the direct correlation function is given by... 

A better approximation, which has become quite popular recently, is the reference hypemetted chain (RHNC) approximation. It makes use of a reference system consisting of a fluid of neutral hard spheres, which is the only potential for which the hrii e function d l, 2) in Eq. (2) is known with sufficient accuracy. If we denote by the subscript 0 a property of the reference system and set h = ho - - Ah, c = cq Ac, v = vq t Av, and d — do -E Ad do, Eq. (5) can be written as... 

FH = Flory-Huggins GF = generalized Flory GFD = generalized Flory dimer HNC = hypemetted chain HTA = high temperature approximation IFJC = ideal freely joined chain ISM = interaction site model LCT = lattice cluster theory MS = Martynov-Sarkisov PMMA = polymethyl methacrylate PRISM = polymer reference interaction site model PVME = polyvinylmethylether PS = polystyrene PY = Percus-Yevick RMMSA = reference molecule mean spherical approximation RMPY = reference molecular Percus-Yevick SANS = small angle neutron scattering SFC = semiflexible chain TPT = thermodynamic perturbation theory. 

---