Linking theoretical and simulation approaches to study fluids in nanoporous media: Molecular dynamics and classical density functional theory

We propose an approach that combines classical density functional theory (DFT) and molecular dynamics (MD) simulation to study fluid behavior in nanopores in contact with bulk fluid (macropores). The approach consists of two principal steps: a DFT calculation of fluid composition and density distribution in a nanopore under specified thermodynamic conditions and an MD simulation of the confined system with obtained characteristics. Thus, we investigate an open system in a grand canonical ensemble. This method allows us to identify both structural and dynamic properties of confined fluid at given bulk con-ditions. Our approach does not require a computationally expensive simulation of a bulk reservoir. This work presents equilibrium density profiles of pure methane, ethane and carbon dioxide and their binary mixtures in slit-like nanopores with carbon walls. Good agreement between the structures obtained by theory and simulation confirms the applicability of the proposed method. (c) 2021 Elsevier Ltd. All rights reserved.