title: Effective density terms in proper integral equations.
abstract: Two complementary routes to a new integral equation theory for site-site molecular fluids are presented. First, a simple approximation to a subset of the atomic site bridge functions in the diagrammatically proper integral equation theory is presented. This in turn leads to a form analogous to the reactive fluid theory, in which the normalization of the intramolecular distribution function and the value of the off-diagonal elements in the density matrix of the proper integral equations are the means of propagating the bridge function approximation. Second, a derivation from a topological expansion of a model for the single-site activity followed by a topological reduction and low-order truncation is given. This leads to an approximate numerical value for the new density coefficient. The resulting equations give a substantial improvement over the standard construction as shown with a series of simple diatomic model calculations.
authors.affiliation: Chemistry Department, University of Houston, Houston, TX 77204-5003, USA.
authors.forename: Kippi M
authors.initials: KM
authors.lastname: Dyer
authors.forename: John S
authors.initials: JS
authors.lastname: Perkyns
authors.forename: B Montgomery
authors.initials: BM
authors.lastname: Pettitt
mesh_terms: D002627:Chemistry, Physical / Q000379:methods*; D045424:Complex Mixtures; D003198:Computer Simulation; D015233:Models, Statistical; D008962:Models, Theoretical; D008968:Molecular Conformation; D012996:Solutions
chemical_list: D045424:Complex Mixtures; D012996:Solutions