  Discrete potentials can describe properly the liquid vapor boundary that is
necessary to model the adsorption of gas molecules in mesoporous systems with
computer simulations. Although there are some works in this subject, the
simulations are still highly time - consuming. Here we show that an efficient
alternative is to use the three - dimensional Ising model, which allows one to
model large systems, with geometries as complex as required that accurately
represent the liquid vapor boundary. In particular, we report molecular
simulations of cylindrical pores of two different geometry, using a discrete
potential. The effect of the length of the pore in the hysteresis loop for a
finite pore and infinite one is studied in detail. Lastly, we compare our
predictions with experimental results and find excellent agreement between the
area of the hysteresis loop predicted for the finite pore and that found in
adsorption/desorption experiments.
