Onsagerian formula for the excluded volume of spherodisks.

By a formal analytic argument based on Minkowski's expression for the isotropic average of the excluded volume of convex bodies, we reproduce the exact formula for the excluded volume of two spherorods-also known by the more traditional name of spherocylinders, which is classically derived through a geometric construction. By applying the same argument to spherodisks, which represent discotic platelets, we obtain a simple explicit formula for their excluded volume, whose validity is corroborated by a shape-reconstruction algorithm.