title: Numerical study of density functional theory with mean spherical approximation for ionic condensation in highly charged confined electrolytes.
abstract: We investigate numerically a density functional theory (DFT) for strongly confined ionic solutions in the canonical ensemble by comparing predictions of ionic concentration profiles and pressure for the double-layer configuration to those obtained with Monte Carlo (MC) simulations and the simpler Poisson-Boltzmann (PB) approach. The DFT consists of a bulk (ion-ion) and an ion-solid part. The bulk part includes nonideal terms accounting for long-range electrostatic and short-range steric correlations between ions and is evaluated with the mean spherical approximation and the local density approximation. The ion-solid part treats the ion-solid interactions at the mean-field level through the solution of a Poisson problem. The main findings are that ionic concentration profiles are generally better described by PB than by DFT, although DFT captures the nonmonotone co-ion profile missed by PB. Instead, DFT yields more accurate pressure predictions than PB, showing in particular that nonideal effects are important to describe highly confined ionic solutions. Finally, we present a numerical methodology capable of handling nonconvex minimization problems so as to explore DFT predictions when the reduced temperature falls below the critical temperature.
authors.affiliation: ANDRA, DRD/EAP, Parc de la croix blanche, 1,7 rue Jean Monnet, 92298 Châtenay-Malabry Cedex, France and University Paris-Est, CERMICS (ENPC), 77455 Marne la Vallée cedex 2, France and Department of Mathematics, Imperial College London, SW7 2AZ London, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Joubaud
authors.affiliation: Sorbonne Universités, UPMC University Paris 06, UMR 8234 PHENIX, 75005 Paris, France and CNRS, UMR 8234 PHENIX, 75005 Paris, France.
authors.forename: O
authors.initials: O
authors.lastname: Bernard
authors.affiliation: CRMD, CNRS-Université d'Orléans, 1B rue de la Férollerie, 45071 Orléans Cedex 02, France.
authors.forename: A
authors.initials: A
authors.lastname: Delville
authors.affiliation: University Paris-Est, CERMICS (ENPC), 77455 Marne la Vallée cedex 2, France.
authors.forename: A
authors.initials: A
authors.lastname: Ern
authors.affiliation: Sorbonne Universités, UPMC University Paris 06, UMR 8234 PHENIX, 75005 Paris, France and CNRS, UMR 8234 PHENIX, 75005 Paris, France.
authors.forename: B
authors.initials: B
authors.lastname: Rotenberg
authors.affiliation: Sorbonne Universités, UPMC University Paris 06, UMR 8234 PHENIX, 75005 Paris, France and CNRS, UMR 8234 PHENIX, 75005 Paris, France.
authors.forename: P
authors.initials: P
authors.lastname: Turq
mesh_terms: D003198:Computer Simulation; D004573:Electrolytes / Q000737:chemistry*; D008956:Models, Chemical; D009010:Monte Carlo Method; D011312:Pressure; D012996:Solutions; D055672:Static Electricity; D013696:Temperature
chemical_list: D004573:Electrolytes; D012996:Solutions