  We study a model Coulomb fluid consisting of dipolar solvent molecules of
finite extent generalizing the point-like Dipolar Poisson-Boltzmann model (DPB)
previously introduced by Coalson and Duncan (J. Phys. Chem 100, 2612 (1996))
and Abrashkin et al. (Phys. Rev. Lett. 99, 077801 (2007)). We formulate a
nonlocal Poisson-Boltzmann equation (NLPB) and study both linear and nonlinear
dielectric response in this model for the case of a single plane geometry. Our
results shed light on the relevance of nonlocal vs nonlinear effects in
continuum models of material electrostatics.
