Effects of a tiny particle trapped in a spherical cavity on fluid structure, contact density, and capillary condensation (a DFT approach)

Abstract

The Modified Fundamental Measure Theory is exploited to investigate the effects of a mobile tiny particle, TP, trapped in a spherical pore on fluid structure, contact density, and capillary condensation. The decreasing and oscillatory behaviors for contact densities versus mobile TP size are observed respectively for hard sphere and Lennard Jones fluids. The capillary condensation of a Lennard Jones confined fluid is investigated in the presence of a mobile TP and compared with those in cases in which the TP is either absent or fixed at the pore center. The configurational chemical potential at which capillary condensation occurs for a fixed TP is smaller than that for a mobile one while both values are still smaller than that for a fluid confined in a spherical pore with no TP. Increasing the size of the mobile TP leads to a decrease in the configurational chemical potential (μ∗) at which capillary condensation occurs and in the coexistence curve width.