Violation of the electroneutrality condition in confined charged fluids

The three point extension to the hypernetted chain--mean spherical theory of liquids is solved for a system formed by two charged plates immersed in a restricted primitive model electrolyte, under several boundary conditions. It is shown that the charged fluid confined by the plates and in equilibrium with a reservoir does not necessarily satisfy the local electroneutrality condition. This depends on the boundary conditions imposed on the plates. The whole system, however, does satisfy a general electroneutrality condition. The plate-plate force is calculated and compared to that from existing Monte Carlo simulations. {} 1996 The American Physical Society.