A theoretical study of the phase diagrams of simple fluids confined withinnarrow pores

In this work the two phase coexistence region for simple fluids confined wi thin slit and cylindrical pores is investigated. The format of this study i nvolves a comparison of the results obtained with the aid of lattice models and molecular dynamics simulations in the near-critical region, and it is shown that the shape of the phase diagram which may be observed depends not only on pore geometry but also on the relative strengths of the fluid-wall and fluid-fluid interaction potentials. In comparison of the results predi cted by lattice-gas theory and molecular dynamics simulation, it is found t hat the lattice model correctly accounts for all of the general features of the phase diagram arising from fluid-wall interaction potential, pore size , and pore shape. In the critical region however there are quantitative dis agreements between lattice theory and molecular simulation due primarily to the mean-field nature of the quasichemical approximation employed in the l attice-gas calculations. Modifications of the lattice model computations wh ich improve the agreement with simulation are presented and discussed.