Density functional theory predictions of adsorption isotherms with hysteresis loops

Adsorption equilibrium is calculated for slit-like pores of various sizes using lattice density functional theory (LDFT). It is shown that LDFT can predict adsorption isotherms with hysteresis loops and that different types of hysteresis loops can be obtained by varying energies of adsorbate–adsorbate and adsorbate–adsorbent interactions for different widths and lengths of slit-like pores. LDFT also predicts hysteresis loops with multiple steps. Though such behavior has not been part of the characterization of isotherms with hysteresis loops, there are experimental data that exhibit steps within hysteresis loops.