Abstract
I give a counterexample to Kleinman's claim concerning certain two-dimensional "slabs" of charge, I categorize according to equivalence six definitions (three from the literature) of average potential Φ and illustrate the results with the spherical (SWS) and regular (WS) Wigner solids, and I treat finite clusters and slabs of three-dimensional cells. Results for the SWS approach those for the WS in the limit of infinite SWS ball radius provided Φ is treated consistently in the two.