Study The Interfacial Properties Of Fluid With Density Functional Theory

In recent years, density functional theory (DFT) has been employed to obtain the structure properties and the thermodynamics properties of inhomogeneous fluids extensively. In this thesis, DFT is used to study the fluid's configuration properties and thermodynamic properties.The analytical radial distribution function and the direct correlation function which are obtained from the FMSA, together with MFMT, are applied to construct the density functional theory. In order to recover the bulk vapor and liquid densities of the Lennard-Jones fluid, the high-order terms of FMSA are included into the DFT to replace the ordinary second-order expansion. The computations of all phase equilibrium properties and direct correlation function for DFT are developed systematically from FMSA.We arrived at the DFT for Lennard-Jones fluid by constructing the excess free energy with MFMT and high-order FMSA. We employ this DFT to study the density profile and surface tension at various temperatures. The method was extended to the associating fluid. The calculated density profiles and interfacial tension are much better than those from ordinary DFT. The results indicates that our theory can capture the character of the associating fluid when compared with molecular simulation data. Furthermore, we do an exploringly research on the interfacial properties of chainlike fluid with attraction. This DFT is a useful theoretic tool for our future study on the interfacial properties of polymeric fluid.