  The pair-correlation functions for fluid ionic mixtures in arbitrary spatial
dimensions are computed in hypernetted chain (HNC) approximation. In the
primitive model, all ions are approximated as non-overlapping hyperspheres with
Coulomb interactions. Our spectral HNC solver is based on a Fourier-Bessel
transform introduced by Talman [J. Comput. Phys., 29, 35 (1978)], with
logarithmically spaced computational grids. Numeric efficiency for arbitrary
spatial dimensions is a commonly exploited virtue of this transform method.
Here, we highlight another advantage of logarithmic grids, consisting in
efficient sampling of pair-correlation functions for highly asymmetric ionic
mixtures. For three-dimensional fluids, ion size- and charge-ratios larger than
one thousand can be treated, corresponding to hitherto computationally not
accessed micrometer-sized colloidal spheres in 1-1 electrolyte. Effective
colloidal charge numbers are extracted from our primitive model results. For
moderately large ion size- and charge-asymmetries, we present Molecular
Dynamics simulation results that agree well with the approximate HNC pair
correlations.
