Topic

# Ionic potential

About: Ionic potential is a research topic. Over the lifetime, 1052 publications have been published within this topic receiving 30064 citations.

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TL;DR: In this paper, the aqueous ionic radii of 35 ions were calculated from published data of the average distances between the ions and the nearest water molecules, obtained by diffraction and computer simulation methods.

Abstract: The aqueous ionic radii of 35 ions have been calculated from published data of the average distances between the ions and the nearest water molecules, obtained by diffraction and computer simulation methods.

1,306 citations

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966 citations

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TL;DR: In this paper, the authors present a method of calculating the electric charge density of glass and silica surfaces in contact with aqueous electrolytes for two cases of practical relevance that are not amenable to standard techniques: surfaces of low specific area at low ionic strength and surfaces interacting strongly with another anionic surface.

Abstract: We present a method of calculating the electric charge density of glass and silica surfaces in contact with aqueous electrolytes for two cases of practical relevance that are not amenable to standard techniques: surfaces of low specific area at low ionic strength and surfaces interacting strongly with a second anionic surface.

813 citations

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TL;DR: In this article, the authors reported the implementation of a finite-difference algorithm which solves the linearized Poisson-Boltzmann equation for molecules of arbitrary shape and charge distribution, including the screening effects of electrolytes.

Abstract: In this paper we report the implementation of a finite-difference algorithm which solves the linearized Poisson-Boltzmann equation for molecules of arbitrary shape and charge distribution and which includes the screening effects of electrolytes. The microcoding of the algorithm on an ST-100 array processor allows us to obtain electrostatic potential maps in and around a protein, including the effects of ionic strength, in about 30 minutes. We have applied the algorithm to a dimer of the protein Cu-Zn superoxide dismutase (SOD) and compared our results to those obtained from uniform dielectric models based on coulombic potentials. We find that both the shape of the protein-solvent boundary and the ionic strength of the solvent have a profound effect on the potentials in the solvent. For the case of SOD, the cluster of positive charge at the bottom of the active site channel produces a strongly enhanced positive potential due to the focusing of field lines in the channel—a result that cannot be obtained with any uniform dielectric model. The remainder of the protein is surrounded by a weak negative potential. The electrostatic potential of the enzyme seems designed to provide a large cross-sectional area for productive collisions. Based on the ionic strength dependence of the size of the positive potential region emanating from the active site and the repulsive negative potential barrier surrounding the protein, we are able to suggest an explanation for the ionic strength dependence of the activity of the native and chemically modified forms of the enzyme.

704 citations

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TL;DR: In this paper, the hydration free energies of ions exhibit an approximately quadratic dependence on the ionic charge, as predicted by the Born model, and the average and fluctuation of the electrostatic potential at charge sites appear as the first coefficients in a Taylor expansion of the free energy of charging.

Abstract: The hydration free energies of ions exhibit an approximately quadratic dependence on the ionic charge, as predicted by the Born model. We analyze this behavior using second-order perturbation theory. The average and the fluctuation of the electrostatic potential at charge sites appear as the first coefficients in a Taylor expansion of the free energy of charging. Combining the data from different charge states (e.g., charged and uncharged) allows calculation of free-energy profiles as a function of the ionic charge. The first two Taylor coefficients of the free-energy profiles can be computed accurately from equilibrium simulations, but they are affected by a strong system-size dependence. We apply corrections for these finite-size effects by using Ewald lattice summation and adding the self-interactions consistently. An analogous procedure is used for the reaction-field electrostatics. Results are presented for a model ion with methane-like Lennard-Jones parameters in simple point charge water. We find t...

650 citations