ANALYSIS OF THE HENDERSON-ABRAHAM-BARKER EQUATION IN THE CASE OF A POLAR LIQUID NEAR A NEUTRAL HARD-WALL

The physical content of the wall-particle direct correlation function c(w)(1), defined from the Ornstein-Zernike equation in the framework o f the Henderson-Abraham-Barker approach, is analyzed in the case of a dipolar-hard-sphere fluid near a pure and dielectric neutral wall. The exact asymptotic behavior of c(w)(1) is established and we show that it is not related to simple physical concepts as, e.g., the image pote ntial. We show that the exact Henderson-Abraham-Barker equation introd uces some bridge diagrams which are more simple graphs in another appr oach. Due to this fact, at least for systems with long range interacti ons, it is misleading to use the usual closures of the theory of homog eneous liquids for c(w)(1). In the case of a dielectric wall, we empha size that the diagrammatic structure of c(w)(1) requires the introduct ion of a three-body Mayer function. The dipolar-hard-sphere liquid is a good candidate for analyzing c(w)(1) because some exact results are known and related to simple electrostatic effects; however, the presen t results are not restricted to this system.