  We develop an efficient Ewald method of molecular dynamics simulation for
calculating the electrostatic interactions among charged and polar particles
between parallel metallic plates, where we may apply an electric field with an
arbitrary size. We use the fact that the potential from the surface charges is
equivalent to the sum of those from image charges and dipoles located outside
the cell. We present simulation results on boundary effects of charged and
polar fluids, formation of ionic crystals, and formation of dipole chains,
where the applied field and the image interaction are crucial. For polar
fluids, we find a large deviation of the classical Lorentz-field relation
between the local field and the applied field due to pair correlations along
the applied field. As general aspects, we clarify the difference between the
potential-fixed and the charge-fixed boundary conditions and examine the
relationship between the discrete particle description and the continuum
electrostatics.
