Nonlocal and nonlinear electrostatics of a dipolar Coulomb fluid

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.