Capillary condensation in pores with energetically heterogeneous walls: Density functional versus Monte Carlo calculations

We investigate adsorption of a Lennard-Jones fluid in slit-like pores with energetically heterogeneous walls by using Grand Canonical Monte Carlo simu lations and a density functional approach. The model of a fluid-wall potent ial is qualitatively similar to that invoked by Rocken et al. (J. Chem. Phy s. 108, 8089, (1999); i.e., it consists of a homogeneous part that varies i n the direction perpendicular to the wall and a periodic part, varying also in one direction parallel to the wall, but in contrast to the above mentio ned work, both parts of the fluid-wall potential are modeled by Lennard-Jon es (9, 3) type functions. The structure of the adsorbed film is characteriz ed by local densities. We evaluate the phase diagrams for several systems c haracterized by different corrugation of the adsorbing potential and discus s the discrepancies between theoretical predictions and computer simulation s. (C) 2001 Academic Press.