  We present Monte Carlo Simulations using an equilibrium lattice-gas model for
the electrosorption of Cl on Ag(100) single-crystal surfaces. Fitting the
simulated isotherms to chronocoulometry experiments, we extract parameters such
as the electrosorption valency gamma and the next-nearest-neighbor lateral
interaction energy phi_nnn. Both coverage-dependent and coverage independent
gamma were previously studied assuming a constant phi_nnn [I. Abou Hamad, Th.
Wandlowski, G. Brown, P.A. Rikvold, J. Electroanal. Chem. 554-555 (2003) 211].
Here, a self-consistent, entirely electrostatic picture of the lateral
interactions with a coverage-dependent phi_nnn is developed, and a relationship
between phi_nnn and gamma is investigated for Cl on Ag(100).
