Monte Carlo simulations and mean-field modeling of electric double layers at weakly and moderately charged spherical macroions

Author(s)

Caetano, Daniel L. Z. ^{[1, 2]} ; Carvalho, Sidney J. de ^[3] ; V. Bossa, Guilherme ^[3] ; May, Sylvio ^[4]

Affiliation

^[1] State Univ Campinas UNICAMP, Inst Chem, BR-13083970 Campinas, SP - Brazil

^[2] State Univ Campinas UNICAMP, Ctr Computat Engn & Sci, BR-13083970 Campinas, SP - Brazil

^[3] Sao Paulo State Univ UNESP, Inst Biosci Humanities & Exact Sci, Dept Phys, BR-15054000 Sao Jose Do Rio Preto, SP - Brazil

^[4] North Dakota State Univ, Dept Phys, Fargo, ND 58108 - USA

• Document type: Journal article
• Source: Physical Review E; v. 104, n. 3 SEP 23 2021.
• Web of Science Citations: 0

Abstract

Monte Carlo simulations are employed to determine the differential capacitance of an electric double layer formed by small size-symmetric anions and cations in the vicinity of weakly to moderately charged macroions. The influence of interfacial curvature is deduced by investigating spherical macroions, ranging from flat to moderately curved. We also calculate the differential capacitance using a previously developed mean-field model where, in addition to electrostatic interactions, the excluded volumes of the ions are taken into account using either the lattice-gas or the Carnahan-Starling equation of state. For both equations of state, we compare the mean-field model for arbitrary curvature with a recently developed second-order curvature expansion. Our Monte Carlo simulations predict an increase in the differential capacitance with growing macroion curvature if the surface charge density is small, whereas for moderately charged macroions the differential capacitance passes through a local minimum. Both mean-field models tend to somewhat overestimate the differential capacitance as compared with Monte Carlo simulations. At the same time, they do reproduce the curvature dependence of the differential capacitance, especially for small surface charge density. Our study suggests that the quality of mean-field modeling does not worsen when weakly or moderately charged macroions exhibit spherical curvature. (AU)

• FAPESP's process: 18/01841-2 - Computational Simulation Studies on the Interaction Between Polyelectrolytes and Macromolecules
• Grantee: Sidney Jurado de Carvalho
• Support Opportunities: Regular Research Grants
• FAPESP's process: 19/19662-0 - Mesoscopic architecture of lignocellulosic fibers
• Grantee: Daniel Lucas Zago Caetano
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 13/08293-7 - CCES - Center for Computational Engineering and Sciences
• Grantee: Munir Salomao Skaf
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 17/21772-2 - Extensions of the Poisson-Boltzmann Theory to the study of the differential capacitance of an electrical double layer
• Grantee: Guilherme Volpe Bossa
• Support Opportunities: Scholarships in Brazil - Post-Doctoral