arXiv subjects

H. Berthoumieux

Publications and source records attributed to H. Berthoumieux.

2 recordsLinked to original sources

arXiv2021

Ion Solvation in Dipolar Poisson models in a dual view

We study the classic problem of ion solvation within the continuum theory of Dipolar-Poisson models. In this approach an ion is treated as a point charge within a sea of point dipoles. Both the standard Dipolar-Poisson model as well as the Dipolar-Poisson-Langevin model, which keeps the dipolar density fixed, are non-convex functionals of the scalar electrostatic potential $ϕ$. Applying the Legendre transform approach introduced by A.C. Maggs [A.C. Maggs, Europhys. Lett. 98, 16012 (2012)], the dual functionals of these models are derived and are given by convex vector-field functionals of the dielectric displacement and the polarization field. We show that the Dipolar-Poisson-Langevin functional generalizes the harmonic polarization functional used in the theory of Marcus for electron transfer rate to nonlinear regimes and can be quantitatively parametrized by molecular dynamics simulations for SPC/E-water.

cond-mat.soft↗

arXiv2020

Electrostatic interactions in water: nonlocal electrostatic approach

Can we avoid molecular dynamics simulations to estimate the electrostatic interaction between charged objects separated by a nanometric distance in water? To answer this question, we develop a continuous model for the dielectric properties of water based on a functional of the polarization. A phenomenological Landau-Ginzburg Hamiltonian for the electrostatic energy of water is parameterized to capture the dipolar correlations in the fluid at the nanometric scale. We show that in this framework, the effective interactions of simple objects such as point charges are analytically tractable. In particular, the derivation of the interaction energy between a solvated charge and a surface can be reduced to a system of linear equations of electrostatic potentials and analytically solved. This approach could thus give access in few calculation lines to data that necessitate long and costly simulations.

cond-mat.soft↗