Modified Ewald Summation Method for Slab Geometries: Application to Donnan Potentials, Confinement Electrostatics, and Titration Simulations.
- 1Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, Porto Alegre, Rio Grande do SulCEP 91501-970, Brazil.
- 2Escola de Química e Alimentos, Universidade Federal do Rio Grande, Rio Grande96203-900, Brazil.
Abstract
Simulating electrochemical systems confined within nanoscale slab geometries is a major challenge due to long-range electrostatic interactions and the breakdown of global charge neutrality when the domain exchanges ions with an external bulk electrolyte reservoir. In this work, we present a grand-canonical simulation framework designed for slab geometries that utilizes a regularized 3D periodic Ewald summation technique to systematically converge to the true 2D periodic Green's function without unphysical cell-width (Lz) dependencies. Unlike traditional grand canonical methods that rely on neutral-pair insertions to maintain a zero net charge, our framework allows the net cell charge to fluctuate by implementing decoupled, single-ion trial moves. This approach bypasses the cooperative sampling bottlenecks that plague neutral-pair insertions inside dense, strongly charged nanopores. Crucially, the method allows us to calculate the Donnan potential (φD) inside the cell, which cannot be accessed directly by any other available simulation method. The Donnan potential acts as a direct microscopic analog to the electromotive force (emf) of a nanoscale electrochemical cell, making the method uniquely suited for iontronic and nanofluidic applications where nonideal ion-ion correlations and strong inhomogeneities modify device potentials. The methodology is validated against exact solutions of the nonlinear Poisson-Boltzmann equation, demonstrating excellent agreement for both local ionic density profiles and self-consistent potentials. Finally, we demonstrate the utility of this framework by simulating charge regulation and surface titration of weak acidic groups at the pore wall.
Related
- Exact periodic electrostatics for latent-charge machine-learning potentials
- Toward Chemical Accuracy in Biomolecular Simulations through Data-Driven Many-Body Potentials: III. A Library of Amino Acid Building Blocks
- Machine Learning-Powered Simulations of Confinement-Driven ¹²⁹ Xe Nuclear Spin Relaxation
- Accuracy and Efficiency Benchmarks of Pretrained Machine Learning Potentials for Molecular Simulations
- Polarizable atomic multipoles for learning long-range electrostatics
BibTeX
@article{levin2026modified,
title = {{Modified Ewald Summation Method for Slab Geometries: Application to Donnan Potentials, Confinement Electrostatics, and Titration Simulations.}},
author = {Yan Levin and Amin Bakhshandeh},
journal = {The journal of physical chemistry. B},
year = {2026},
month = oct,
doi = {10.1021/acs.jpcb.6c05163},
url = {https://europepmc.org/article/MED/42916703},
note = {CC BY},
}
RIS
TY - JOUR
TI - Modified Ewald Summation Method for Slab Geometries: Application to Donnan Potentials, Confinement Electrostatics, and Titration Simulations.
AU - Yan Levin
AU - Amin Bakhshandeh
PY - 2026
DA - 2026/10/01
JO - The journal of physical chemistry. B
DO - 10.1021/acs.jpcb.6c05163
UR - https://europepmc.org/article/MED/42916703
AB - Simulating electrochemical systems confined within nanoscale slab geometries is a major challenge due to long-range electrostatic interactions and the breakdown of global charge neutrality when the domain exchanges ions with an external bulk electrolyte reservoir. In this work, we present a grand-canonical simulation framework designed for slab geometries that utilizes a regularized 3D periodic Ewald summation technique to systematically converge to the true 2D periodic Green's function without unphysical cell-width (Lz) dependencies. Unlike traditional grand canonical methods that rely on neutral-pair insertions to maintain a zero net charge, our framework allows the net cell charge to fluctuate by implementing decoupled, single-ion trial moves. This approach bypasses the cooperative sampling bottlenecks that plague neutral-pair insertions inside dense, strongly charged nanopores. Crucially, the method allows us to calculate the Donnan potential (φD) inside the cell, which cannot be accessed directly by any other available simulation method. The Donnan potential acts as a direct microscopic analog to the electromotive force (emf) of a nanoscale electrochemical cell, making the method uniquely suited for iontronic and nanofluidic applications where nonideal ion-ion correlations and strong inhomogeneities modify device potentials. The methodology is validated against exact solutions of the nonlinear Poisson-Boltzmann equation, demonstrating excellent agreement for both local ionic density profiles and self-consistent potentials. Finally, we demonstrate the utility of this framework by simulating charge regulation and surface titration of weak acidic groups at the pore wall.
SN - 1520-6106
SN - 1520-5207
ER -