Statistical mechanics of surface tension and Tolman length of dipolar fluids

The Tolman length (δ_∞) characterizes the first-order correction to the surface tension (σ_∞) due to curvature of the interface. Statistical mechanical expressions for σ_∞ and δ_∞ were derived previously by Blokhuis and Bedeaux [Physica A 1992, 184, 42] for nonpolar fluids. Here Blokhuis and Bedeaux's approach is extended to dipolar fluids. Two approximations to the pair correlation function are employed, and their effects on σ_∞ and δ_∞ are examined. The dependence of σ_∞ and δ_∞ on temperature and dipole moment is also explored. It is found that σ_∞ increases with the dipole moment while |δ_∞| decreases as the dipole moment is increased. The sign of δ_∞ is, however, negative.