Work

Large deviations of ionic currents in dilute electrolytes

Year: 2025

Type: article

Abstract: We evaluate the exponentially rare fluctuations of the ionic current for a dilute electrolyte by means of macroscopic fluctuation theory. We consider the fluctuating hydrodynamics of a fluid electrolyte described by a stochastic Poisson-Nernst-Planck equation. We derive the Euler-Lagrange equations that dictate the optimal concentration profiles of ions conditioned on exhibiting a given current, whose form determines the likelihood of that current in the long-time limit. For a symmetric electrolyte under small applied voltages, number density fluctuations are small, and ionic current fluctuations are Gaussian with a variance determined by the Nernst-Einstein conductivity. Under large applied potentials, the ionic current distribution is generically non-Gaussian. Its structure is constrained thermodynamically by Gallavotti-Cohen symmetry and the thermodynamic uncertainty principle.

Source: The Journal of Chemical Physics

DOI: 10.1063/5.0297861

Authors: Jafar Farhadi, David T. Limmer

Institutions: University of California, Berkeley, Lawrence Berkeley National Laboratory, Kavli Energy NanoScience Institute

Language: English

Topic: Advanced Thermodynamics and Statistical Mechanics

Subfield: Statistical and Nonlinear Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: U.S. Department of Energy, Basic Energy Sciences

Awards: G1286236842, G30714459, G3083819904, G42916606, G969889393