A functional perturbation theory for nonuniform molecular fluids. Effect of a weak dipole in a liquid–vapor interphase

A perturbation theory for nonuniform molecular fluids using the functional formalism is developed. Approximate expressions are written down for axial molecules using the spherical harmonic expansion. Under certain approximations Tarazona–Navascués and Haile et al. perturbation theories are recovered. Numerical calculation for the molecular orientation in liquid–vapor interphase of an axial fluid with a weak dipole is included.