Smoluchowski equation and the colloidal charge reversal

Diehl, Alexandre; Levin, Yan

doi:10.1063/1.2222372

Cited by 70 publications

(74 citation statements)

References 49 publications

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“…Indeed, the far-field LMF term, βΔG LMF = −1,049, whereas βĜ R = −244. The LMF result βĜ = −1,293 is in very good agreement with that determined using conventional techniques (33), βĜ Ewald = −1,294.…”

Section: Solvation and Overcharging In Colloidal Systemssupporting

confidence: 83%

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Long-ranged contributions to solvation free energies from theory and short-ranged models

Remsing

Liu

Weeks

2016

Proc. Natl. Acad. Sci. U.S.A.

161

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Long-standing problems associated with long-ranged electrostatic interactions have plagued theory and simulation alike. Traditional lattice sum (Ewald-like) treatments of Coulomb interactions add significant overhead to computer simulations and can produce artifacts from spurious interactions between simulation cell images. These subtle issues become particularly apparent when estimating thermodynamic quantities, such as free energies of solvation in charged and polar systems, to which long-ranged Coulomb interactions typically make a large contribution. In this paper, we develop a framework for determining very accurate solvation free energies of systems with long-ranged interactions from models that interact with purely short-ranged potentials. Our approach is generally applicable and can be combined with existing computational and theoretical techniques for estimating solvation thermodynamics. We demonstrate the utility of our approach by examining the hydration thermodynamics of hydrophobic and ionic solutes and the solvation of a large, highly charged colloid that exhibits overcharging, a complex nonlinear electrostatic phenomenon whereby counterions from the solvent effectively overscreen and locally invert the integrated charge of the solvated object.mean field theory | free energy calculations | density functional theory | hydrophobicity | solvation S olvation thermodynamics underlies a vast array of important processes, ranging from protein folding (1, 2) and ligand binding (3) to self-assembly at interfaces (4). Thus, understanding solvation, and driving forces rooted in solvation, has been a focus of chemistry and physics for over a century (5, 6).Quantitatively successful theories of self-solvation and solvophobic solvation in simple fluids have been developed (7-16). However, a generally useful analytic approach for solvation in complex charged and polar environments is lacking, and solvation is typically studied with computer simulations. Contributions from the long-ranged components of Coulomb interactions in periodic images of the simulation cell are typically evaluated using computationally intense Ewald and related lattice summation techniques (17). These methods generate distorted, system size-dependent interaction potentials (18) and do not scale well in massively parallel simulations (19), adding considerable computational overhead. Moreover, artifacts can arise from spurious interactions between the periodic images of solutes, as observed for proteins in water (20).The local molecular field (LMF) theory of nonuniform fluids is a promising avenue for substantially improving free energy calculations by removing many of the computational and conceptual burdens associated with long-ranged interactions (14,21). LMF theory prescribes a way to accurately determine the structure of a full system with long-ranged intermolecular interactions in a general single particle field by studying a simpler mimic system wherein particles interact with short-ranged intermolecular interactions only. An effective...

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Section: Solvation and Overcharging In Colloidal Systemssupporting

confidence: 83%

“…33. The charge is uniformly smeared over the colloid surface, and the colloid and counterions are modeled as charged WCA species (7).…”

Section: Solvation and Overcharging In Colloidal Systemsmentioning

confidence: 99%

Long-ranged contributions to solvation free energies from theory and short-ranged models

Remsing

Liu

Weeks

2016

Proc. Natl. Acad. Sci. U.S.A.

161

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show abstract

“…Martin-Molina et al [24,25] simulate the overcharging at a planar wall in salty environment under more realistic conditions, which should be valid in the limit of large colloids. Diehl and Levin [26] have performed Monte Carlo simulations of a spherical colloid, where the ζ-potential is measured.…”

Section: Introductionmentioning

confidence: 99%

Simulation of charge reversal in salty environments: Giant overcharging?

Lenz

Holm

2008

Eur. Phys. J. E

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Abstract. We have performed MD simulations of a highly charged colloid in a solution of 3:1 and additional 1:1 salt. The dependency of the colloid's inverted charge on the concentration of the additional 1:1 salt has been studied. Most theories predict, that the inverted charge increases when the concentration of monovalent salt grows, up to what is called giant overcharging, while experiments and simulational studies observe the opposite. Our simulations agree with the experimental findings and shed light onto the weaknesses of the theories.

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“…These values were evaluated as volume % and the peak mean >90%, presented in graph form. The zeta potential of each material was calculated in negative millivolts using the Smoluchowski equation (Doane et al, 2012;Diehl and Levin, 2006). Data were analyzed using a one-way ANOVA, followed by a Tukey's post-analysis and graphed using Graph Pad Prism 5 (GraphPad Software, San Diego, CA).…”

Section: Physical Characterizationmentioning

confidence: 99%