Field-Theoretic Approaches to Classical Charged Systems

Holm, Christian; Moreira, André G.; Netz, Roland R.

doi:10.1007/978-94-010-0577-7_11

Cited by 18 publications

(27 citation statements)

References 35 publications

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“…Figure 4(a) shows the difference between n(z) and n PB (z) for Ξ = 1, 10, 10 2 , and 10 4 , as calculated numerically in the TCMF model (continuous lines). These results are compared with simulation data (symbols) [13,24].…”

Section: Results For N(z)mentioning

confidence: 99%

Test-charge theory for the electric double layer

2004

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We present a model for the ion distribution near a charged surface, based on the response of the ions to the presence of a single test particle. Near an infinite planar surface this model produces the exact density profile in the limits of weak and strong coupling, which correspond to zero and infinite values of the dimensionless coupling parameter. At intermediate values of the coupling parameter our approach leads to approximate density profiles that agree qualitatively with MonteCarlo simulation. For large values of the coupling parameter our model predicts a crossover from exponential to algebraic decay at large distance from the charged plate. Based on the test charge approach we argue that the exact density profile is described, in this regime, by a modified mean field equation, which takes into account the interaction of an ion with the ions close to the charged plate.

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Section: Results For N(z)mentioning

confidence: 99%

Test-charge theory for the electric double layer

2004

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“…In addition, we will compare our results to the strong coupling (SC) theory of Naji, Moreira and Netz [23,24,26]. Also in our SC calculations, we confined the two rods in a cylinder of diameter 4×D, as we did in our computer simulations.…”

Section: Systems With Finite Temperaturementioning

confidence: 87%

“…We compared these configurations both to the strong-coupling (SC) theory of Moreira and Netz [23,24], and to our T = 0 results. Unlike our zero-temperature calculations, the SC limit provides good predictions for the temperature dependence, however, our T = 0 predictions cover a wider range of system geometries.…”

Section: Discussionmentioning

confidence: 99%

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Interactions of like-charged rods at low temperatures: Analytical theory vs. simulations

Arnold

Holm

2008

Eur. Phys. J. E

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Abstract. We investigate a system consisting of two like-charged infinitely long rods and neutralizing counterions at low temperatures, using both analytic theory and simulations. With some reasonable approximations we can analytically solve for several ground-state structures of the model, starting with states where all counterions are lined up in the gap between the rods, over planar configurations, where the counterions are divided up into a fraction which resides between the rods, and counterions which are located on the outer surfaces, up to configurations which cover the full rod surfaces. Using parallel tempering simulations, we are able to study the system over a wide range of temperatures. At low temperatures we find good agreement with our T = 0 results. At higher temperatures, the strong coupling (SC) theory delivers qualitatively better results. We furthermore demonstrate that for the SC theory and our ground-state approximations to yield quantitative agreement, three parameters are required to be large, the strong-coupling parameter Ξ, the Rouzina-Bloomfield parameter, and the ratio of the average distance of the counterions to the radius of the rods. In the case of the latter ratio being small, our T = 0 results show better agreement with the simulation data at very low temperatures.

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“…In this regime, multivalent counterions collapse the brush in the form of linked clusters. Nematic order emerges at high grafting densities, resulting is an abrupt increase of the brush height.Electrostatic correlation effects of highly charged macro-ions in aqueous solutions have recently attracted much attention [1]. Novel phenomena such as charge inversion and likecharge attraction, which cannot be understood within the Poisson-Boltzmann theory, appear to play a key role in biological processes such as DNA packaging [2] and cell scaffolding dynamics [3].…”

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confidence: 99%

Rod-like polyelectrolyte brushes with mono- and multivalent counterions

Fazli¹,

Golestanian²,

Hansen³

et al. 2006

Europhys. Lett.

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Abstract. -A model of rod-like polyelectrolyte brushes in the presence of monovalent and multivalent counterions but with no added-salt is studied using Monte Carlo simulation. The average height of the brush, the histogram of rod conformations, and the counterion density profile are obtained for different values of the grafting density of the charge-neutral wall. For a domain of grafting densities, the brush height is found to be relatively insensitive to the density due to a competition between counterion condensation and inter-rod repulsion. In this regime, multivalent counterions collapse the brush in the form of linked clusters. Nematic order emerges at high grafting densities, resulting is an abrupt increase of the brush height.Electrostatic correlation effects of highly charged macro-ions in aqueous solutions have recently attracted much attention [1]. Novel phenomena such as charge inversion and likecharge attraction, which cannot be understood within the Poisson-Boltzmann theory, appear to play a key role in biological processes such as DNA packaging [2] and cell scaffolding dynamics [3]. Such correlations, and their role in determining the overall structural properties of the system, are most pronounced in high density polyelectrolyte solutions where the charge "patterns" that form due to the correlations strongly interact with each other. If the polyelectrolyte is sufficiently stiff in its backbone structure [such as DNA and filamentous actin (F-actin)], a geometric constraint is imposed on the charges in each polyelectrolyte segment to adopt a more or less linear configuration, which makes a solution of such rod-like polyelectrolytes a patterned matrix for the counterions (that is, the ions of opposite charge that are present to neutralize the overall solution). The interplay between these correlations and patterns can lead to novel structural and dynamical properties [4][5][6][7], the study of which could be useful in understanding the biological phenomena mentioned above as well as designing functional biomimetic materials.A common realization of such high density assemblies occurs in polyelectrolyte brushes [8], where charged polymers are end-grafted to surfaces. While polyelectrolyte brushes have been mostly studied because of their role in stabilization of colloidal suspensions, understanding their structural properties could help us in a variety of problems in biophysics and -technology. A case in point is filamentous microtubules, i.e. rod-like structures build from tubulin monomers with charged C-terminal amino-acid tails extending from the filament core [9]. The C-terminal tails seem to play key roles in microtubule function, e.g. in connection with binding of microtubule-associated proteins and processivity of the molecular p-1

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Field-Theoretic Approaches to Classical Charged Systems

Cited by 18 publications

References 35 publications

Test-charge theory for the electric double layer

Test-charge theory for the electric double layer

Interactions of like-charged rods at low temperatures: Analytical theory vs. simulations

Rod-like polyelectrolyte brushes with mono- and multivalent counterions

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