By capturing the correct geometrical features, the fundamental-measure free-energy density functional [Y. Rosenfeld, Phys. Rev. Lett. 63, 980 (1989); J. Chem. Phys. 98, 8126 (1993)] leads to an accurate description of the general inhomogeneous simple (‘‘atomic’’) fluid. It is based on the convolution decomposition of the excluded volume for a pair of spheres in terms of characteristic functions for the geometry of the individual spheres. By relating that convolution decomposition for spheres with the Gauss-Bonnet theorem for general convex bodies, the fundamental-measure functional is made applicable to fluids of asymmetric molecules.

DOI:https://doi.org/10.1103/PhysRevE.50.R3318