Simulation Studies for Porosity and Specific Surface Area in the Penetrable-Concentric-Shell Model Pore

have taken place in parallel with an improvement in our understanding of the molecular structure of both confined fluids and porous media. For both theoretical and practical approaches in this area,1-3 one of the commonly used pore systems is the random pore model in which the solid matrix is represented as assemblies of rigid hard-spheres randomly distributed in the pore phase. The concept of the random bed of spheres becomes more useful if the solid spheres are allowed to be partly overlapped or interpenetrated one another. Such a random pore system is the so-called ‘cherry-pit model ’ or ‘penetrable-concentric-shell (PCS) model’.4-7 In the PCS model pore itself, each sphere of diameter σ is composed of a hard-core of diameter λσ (0 λ 1). The PCS model is versatile to construct various interpenetrable-sphere systems by varying the degree of impenetrability fac-tor λ. The two extreme limits of the impenetrability parame-ters, λ = 0 and λ = 1, respectively, correspond to the cases of fully penetrable and totally impenetrable spheres. The latter can be employed in the model systems of random pore media with a discontinuous solid phase and the former in those of materials possessing a continuous solid phase. For statistically homogeneous media, the simplest mor-phological quantities are the porosity and the specific sur-face area. As for the PCS model pore, Rikvold and Stell4,5 has obtained the analytical expression for low-order struc-tural correlation functions by establishing an isomorphism between the PCS model and the scaled-particle theory. For any arbitrary impenetrability factor 0λ1, the porosity φ, which is the pore volume fraction to the total system vol-ume, can be represented a