Gibbs ensemble Monte Carlo simulation of LJ fluid in cylindrical pore with energetically heterogeneous surface

The energetic heterogeneity effect of a solid surface on the phase behavior of a confined fluid within a narrow cylindrical pore was studied by means of Gibbs Ensemble Monte Carlo (GEMC) and canonical ensemble Monte Carlo (MC) simulations. The energetic heterogeneity was modeled as a local adsorbing site, and all the interactions considered were described by Lennard-Jones (LJ) potentials, i.e. 12-6 and 9-3 type. From the changes in the apparent shapes of isotherms, energetic heterogeneity on the solid surface was found to smear the phase transition region. The energetic heterogeneity of the solid internal surface causes an additive effect to pull the fluid particles toward the solid surface in the entire relative pressure region, leading to higher packing of the fluid particle layered in the vicinity of the pore wall compared with the homogeneous surface case at the same mean fluid density within the pore.