Approximation of the structure factor for nonspherical hard bodies using polydisperse spheres

A new method for approximation of the structure factor for nonspherical hard bodies is suggested. It is shown that for moderate deviation from spherical symmetry the structure factor may be approximated by the structure factor for a size distribution of spheres. The distribution of spheres should be selected to give agreement between the excluded volume distance distribution functions for the two cases. As the excluded volume distance distribution may be calculated by Monte Carlo simulation for any particle and as a semi-analytical expression exists for the excluded volume distance distribution of a size distribution of spheres, it should be possible to apply the method to any shape of molecule. For ellipsoids of axial ratios between 0.5 and 2.0 a simple approximate expression is given for the parameters of the matching size distribution.