title: Beyond Poisson-Boltzmann: Numerical Sampling of Charge Density Fluctuations.
abstract: We present a method aimed at sampling charge density fluctuations in Coulomb systems. The derivation follows from a functional integral representation of the partition function in terms of charge density fluctuations. Starting from the mean-field solution given by the Poisson-Boltzmann equation, an original approach is proposed to numerically sample fluctuations around it, through the propagation of a Langevin-like stochastic partial differential equation (SPDE). The diffusion tensor of the SPDE can be chosen so as to avoid the numerical complexity linked to long-range Coulomb interactions, effectively rendering the theory completely local. A finite-volume implementation of the SPDE is described, and the approach is illustrated with preliminary results on the study of a system made of two like-charge ions immersed in a bath of counterions.
authors.affiliation: Institut de Physique Théorique, Université Paris Saclay, CEA, UMR3681 du CNRS, F-91191 Gif-sur-Yvette, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Poitevin
authors.affiliation: Unit of Structural Dynamics of Macromolecules, UMR 3528 du CNRS, Institut Pasteur, 75015 Paris, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Delarue
authors.affiliation: Institut de Physique Théorique, Université Paris Saclay, CEA, UMR3681 du CNRS, F-91191 Gif-sur-Yvette, France.|Beijing Computational Science Research Center, Haidian District, Beijing 100094, China.
authors.forename: Henri
authors.initials: H
authors.lastname: Orland
mesh_terms: D003198:Computer Simulation; D007477:Ions / Q000737:chemistry*; D008962:Models, Theoretical; D012997:Solvents / Q000737:chemistry*
chemical_list: D007477:Ions; D012997:Solvents