  Electrostatic correlation effects in inhomogeneous symmetric electrolytes are
investigated within a previously developed electrostatic self-consistent (SC)
theory (R.R. Netz and H. Orland, Eur. Phys.J. E 11, 301 (2003)). To this aim,
we introduce two computational approaches that allow to solve the SC equations
beyond the loop expansion. Both approaches can handle the case of
dielectrically discontinuous boundaries where the one-loop theory is known to
fail. By comparing the theoretical results obtained from these schemes with the
results of the MC simulations that we ran for ions at neutral single dielectric
interfaces as well as with previous MC data for charged interfaces, we first
show that the weak coupling (WC) Debye-Huckel (DH) theory remains
quantitatively accurate up to the bulk ion density rhob=0.01 M, whereas the SC
theory exhibits a good quantitative accuracy up to rhob=0.2 M. Then, we derive
from the perturbative SC scheme the one-loop theory of asymmetrically
partitioned salt systems around a dielectrically homogeneous charged surface.
It is shown that correlation effects originate in these systems from a
competition between the salt screening loss at the interface driving the ions
to the bulk region, and the interfacial counterion screening excess attracting
them towards the surface. In the case of weak surface charges, the interfacial
salt screening loss is the dominant effect. As a result, correlations decrease
the MF density of both coions and counterions. With increasing surface charge,
the surface-attractive counterion screening excess starts to dominate, and
correlation effects amplify in this regime the MF density of both type of ions.
We also show that at a characteristic value of the electrostatic coupling
parameter, electrostatic correlations result in a charge inversion effect.
