Surface Structure of a Square-Well Fluid

Abstract

The perturbation expansion for fluids is formulated as an expansion of the chemical potential. The interface density profile between the uniform bulk phases of a square‐well fluid is obtained by requiring that the chemical potential is constant in the interface. The profile is compared with the profile obtained from the Born‐Green‐Yvon‐Bogolyubov integrodifferential equation in the density and with the profile obtained by minimizing the excess free energy of the interface. The density profiles obtained from the three different approaches are all in mutual agreement and show that the interface density decreases monotonically and rapidly for temperatures far from the critical point.