Adsorption of fluids: simple theories for the density profile in a fluid near an adsorbing surface

Abstract

Two simple theories of fluid adsorption are discussed. One starts from the first equation of the BBGKY-hierarchy whereas the other considers a reference system in which the fluid is bounded by a hard wall, and the attractive potential is added with a coupling parameter. For the latter theory numerical results are presented for the density profile and the integrated surface excess over a wide range of fluid densities. These results are compared with those of asymptotic theories. The problem of the density profile of the reference system is considered.