WERTHEIM CLUSTER DEVELOPMENT OF FREE-ENERGY FUNCTIONALS FOR GENERAL NEAREST-NEIGHBOR INTERACTIONS IN D=1

We develop a particle cluster technique for representing the equilibri um thermodynamics of an inhomogeneous multispecies classical fluid in one dimension with nearest-neighbor interactions. The corresponding fr ee energy functionals take on the general Wertheim association form an d make contact with the Widom insertion argument. Application is made to adhesive rod mixtures, for which first-order thermodynamic perturba tion theory is seen to be exact, and to more general interactions, suc h as the square well, in which activity is no longer a local functiona l of the density and explicit relations must be generated by recursion . For a fluid on a loop, auxiliary two-point feedback functions appear , which correct the simply connected form. (C) 1996 American Institute of Physics.