  It is well known that the Poisson-Boltzmann (PB) equation yields the exact
counterion density around charged objects in the weak coupling limit. In this
paper we generalize the PB approach to account for coupling of arbitrary
strength by making use of Tsallis q-exponential distributions. Both the weak
coupling and the strong coupling limits are reproduced. For arbitrary coupling
we also provide simple analytical expressions which are compared to recent
Monte Carlo simulations by A. G. Moreira and R. R. Netz [Europhys. Lett. 52
(2000) 705]. Excellent agreement with these is obtained.
