  We consider heavy neutral atoms of atomic number $Z$ modeled with kinetic
energy $(c^2p^2+c^4)^{1/2}-c^2$ used already by Chandrasekhar. We study the
behavior of the one-particle ground state density on the length scale $Z^{-1}$
in the limit $Z,c\to\infty$ keeping $Z/c$ fixed. We give a short proof of a
recent result by the authors and Barry Simon showing the convergence of the
density to the relativistic hydrogenic density on this scale.
