A replica reference interaction site model theory for a polar molecular liquid sorbed in a disordered microporous material with polar chemical groups

We develop a replica generalization of the reference interaction site model (replica RISM) integral equation theory to describe the structure and ther modynamics of quenched-annealed systems comprising polar molecular species. It provides a successful approach to realistic models of molecular liquids , and properly allows for the effect of a quenched disordered matrix on the sorbed liquid. The description can be extended to an electrolyte solution in a disordered material containing charged chemical functionalities that d etermine its adsorption character. The replica reference interaction site m odel (RISM) equations are complemented with the hypernetted chain (HNC) clo sure and its partial linearization (PLHNC), adequate to ionic and polar mol ecular liquids. In these approximations, the excess chemical potentials are derived in a closed analytical form. We extend the description to a quench ed-annealed system with soft-core interaction potentials between all specie s, in which the liquid and matrix equilibrium distributions are characteriz ed in general by two different temperatures. The replica RISM/PLHNC-HNC the ory is applied to water sorbed in a quenched disordered microporous network of atoms associated into interconnected branched chains, with activating p olar groups grafted to matrix chains. The results are in qualitative agreem ent with experiment for water confined in disordered materials. (C) 2001 Am erican Institute of Physics.