  Based on fundamental measure theory, a Helmholtz free energy density
functional for three-component mixtures of hard spheres with general,
non-additive interaction distances is constructed. The functional constitutes a
generalization of the previously given theory for binary non-additive mixtures.
The diagrammatic structure of the spatial integrals in both functionals is of
star-like (or tree-like) topology. The ternary diagrams possess a higher degree
of complexity than the binary diagrams. Results for partial pair correlation
functions, obtained via the Ornstein-Zernike route from the second functional
derivatives of the excess free energy functional, agree well with Monte Carlo
simulation data.
