Liquids in equilibrium: beyond the hypernetted chain.
Density functional techniques are used to derive a charging expression for the non-uniform density of a molecular liquid. In the atomic limit the equation reduces to an exact form due to Fixman. The theory is simplified greatly via a physical approximation that accounts for three-body correlations beyond those included in the hypernetted chain (HNC) closure of the Ornstein-Zernike (OZ) equation. The radial distribution function is obtained as a special case. The theory is tested by examining the phase behavior of two fundamental complex fluids: the homopolymer blend and diblock copolymer melts. For the former it is found, contrary to HNC theory and its molecular generalizations, that a critical temperature Tc is predicted from the structure route. This To scales linearly with degree of polymerization N in agreement with Flory theory. The simplest form of the theory can be considered as a way to incorporate attractive interactions within a formalism that is very similar to that of the OZ or reference interaction site model (RISM). The relevance of the theory to charged liquids is also discussed.
Donley
J P
JP
The Boeing Company, Huntington Beach, CA 92647, USA. jdonley@mailaps.org
D003198:Computer Simulation; D004735:Energy Transfer; D008956:Models, Chemical; D008958:Models, Molecular; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry*
D011108:Polymers; D012996:Solutions