A Molecular Dynamics Study of Aqueous Solutions V. Angular Distribution of the Water Dipoles in the Hydration Shells of Various Alkali-and Halide Ions

1976 ◽  
Vol 31 (9) ◽  
pp. 1073-1076
Author(s):  
K. Heinzinger
Keyword(s):  
Molecular Dynamics ◽  
Angular Distribution ◽  
Aqueous Solutions ◽  
Angular Distributions ◽  
Water Molecules ◽  
Halide Ions ◽  
Nacl Solution ◽  
Hydration Shells

Abstract The angular distributions of the water dipoles have been calculated from molecular dynamics runs for the first hydration shells of various ions in 2.2 molal LiJ, LiCl, NaCl, CsCl and CsF solutions and in a 0.55 molal NaCl solution. It is shown how the distributions depend on the size of the shell taken around each ion. The results give no indication for the existence of desoriented water molecules in the immediate neighbourhood of the ions.

A Molecular Dynamics Study of Aqueous Solutions

1976 ◽  
Vol 31 (5) ◽  
pp. 476-481 ◽  
Author(s):  
P. C. Vogel ◽  
K. Heinzinger
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solutions ◽  
Internal Pressure ◽  
Chloride Ions ◽  
Water Molecules ◽  
Sodium Ions ◽  
Nacl Solution ◽  
Hydration Shells

Abstract Results of a molecular dynamics study of a 0.55 molal aqueous NaCl solution are reported. The basic periodic box contained 200 water molecules, 2 sodium ions and 2 chloride ions. The calculated properties of this solution are compared with those obtained previously for a 2.2 molal NaCl solution. The formation of second hydration shells, an increase of the number of water molecules in the first hydration shells, and a release of internal pressure are the main changes connected with a decrease of the concentration.

A Molecular Dynamics Study of Aqueous Solutions

1976 ◽  
Vol 31 (5) ◽  
pp. 463-475 ◽  
Author(s):  
K. Heinzinger ◽  
P. C. Vogel
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solutions ◽  
Correlation Functions ◽  
Elevated Temperatures ◽  
Pure Water ◽  
Pair Correlation ◽  
Lone Pair ◽  
Water Molecules ◽  
Pair Correlation Functions ◽  
Hydration Shells

Abstract Results of a molecular dynamics study of aqueous solutions of LiJ, LiCl, NaCl, CsCl and CsF are reported. The basic periodic box contained 200 water molecules, 8 cations and 8 anions, equivalent to 2.2 molal solutions. Static properties of the first hydration shells of the ions are discussed in detail on the basis of radial pair correlation functions, average potential energies of the water molecules and pair interaction energy distributions. The calculations lead to the conclusion that in the first hydration shells a lone pair orbital of the water molecule is directed towards the cation while a hydrogen atom points towards the anion. In the five alkali halide solutions investigated ion pairing occurs only with CsF. The hydration numbers, when defined as the volume integrals of the ion-water radial pair correlation functions up to the first minimum, increase with increasing ion size and depend on the size of the counterion. The water-water interactions in the solutions show not only features of pure water at elevated temperatures but also of pure water under compresion. The agreement between calculated and measured self diffusion coefficients is still insufficient.

scholarly journals Origin and control of ionic hydration patterns in nanopores

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Miraslau L. Barabash ◽  
William A. T. Gibby ◽  
Carlo Guardiani ◽  
Alex Smolyanitsky ◽  
Dmitry G. Luchinsky ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Distribution Functions ◽  
Water Molecules ◽  
Surrounding Water ◽  
Ionic Hydration ◽  
Hydration Shells ◽  
Water Layers ◽  
Dynamics Simulations ◽  
And Control

AbstractIn order to permeate a nanopore, an ion must overcome a dehydration energy barrier caused by the redistribution of surrounding water molecules. The redistribution is inhomogeneous, anisotropic and strongly position-dependent, resulting in complex patterns that are routinely observed in molecular dynamics simulations. Here, we study the physical origin of these patterns and of how they can be predicted and controlled. We introduce an analytic model able to predict the patterns in a graphene nanopore in terms of experimentally accessible radial distribution functions, giving results that agree well with molecular dynamics simulations. The patterns are attributable to a complex interplay of ionic hydration shells with water layers adjacent to the graphene membrane and with the hydration cloud of the nanopore rim atoms, and we discuss ways of controlling them. Our findings pave the way to designing required transport properties into nanoionic devices by optimising the structure of the hydration patterns.

scholarly journals SPECTRAL FEATURES AND HYDROGEN BOND STRUCTURE OF AQUEOUS SOLUTIONS OF ETHANOL

2021 ◽  
pp. 30-33
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bonds ◽  
Aqueous Solutions ◽  
Gaseous Medium ◽  
Water Molecules ◽  
Structural Reorganization ◽  
Intermolecular Hydrogen Bonds ◽  
Method Of Molecular Dynamics ◽  
Combined Use ◽  
Structure Of Aqueous Solutions

The aim of this work is develop an approach that makes it possible to study the spectral properties and structure of intermolecular hydrogen bonds in aqueous solutions of ethanol formed in systems whose existence in a gaseous medium or an isolated state is practically impossible. This approach bases on the combined use of infrared spectroscopy and molecular dynamics (MD) methods. An analysis give the structural reorganization of water molecules depending on the concentration of ethanol alcohol. It has been shown that the method of molecular dynamics with classical force fields makes it possible to explicitly take into account the molecules of the solvent and solute, and, thus, to investigate hydrogen bonds in the system and to interpret with the experimental data obtained by vibrational spectroscopy.

A Molecular Dynamics Study of Ionic Hydration Near a Platinum Surface

1991 ◽  
Vol 46 (10) ◽  
pp. 876-886 ◽  
Author(s):  
J. Seitz-Beywl ◽  
M. Poxleitner ◽  
K. Heinzinger
Keyword(s):  
Boundary Layer ◽  
Molecular Dynamics ◽  
Distribution Functions ◽  
Water Molecules ◽  
Molecular Orbital Calculations ◽  
Platinum Surface ◽  
Average Temperature ◽  
Ionic Hydration ◽  
Hydration Shells ◽  
Dynamics Simulations

AbstractTwo Molecular Dynamics simulations have been performed where a Pt(100) surface is covered with three layers of water molecules and a lithium or an iodide ion is placed additionally in the boundary layer. The flexible BJH model of water is employed in the simulations and the ion-water, platinum-water and platinum-ion potentials are derived from molecular orbital calculations. The simulations extended over 7.5 ps at an average temperature of 298 K. The effect of the Pt(100) surface on the ionic hydration is demonstrated by the comparison of the radial distribution functions, the orientation of the water molecules and their geometrical arrangement in the first hydration shells of the ions in the boundary layer with those in a 2.2 molal bulk Lil solution.

Ion Hydration Under Pressure: A Molecular Dynamics Study

2013 ◽  
Vol 68 (1-2) ◽  
pp. 112-122 ◽  
Author(s):  
Maksym Druchok ◽  
Myroslav Holovko
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solutions ◽  
Dynamic Properties ◽  
Ion Hydration ◽  
Coordination Numbers ◽  
Self Diffusion ◽  
Velocity Autocorrelation ◽  
Hydration Behaviour ◽  
Hydration Shells ◽  
Dynamics Simulations

This study is intended to elucidate the role of pressure on the hydration behaviour of ions in aqueous solutions. Molecular dynamics simulations were performed for systems modelling CsF, CsCl, CsBr, and CsI aqueous solutions under ‘normal’ (105 Pa, 298 K) and ‘high pressure’ (4 ·109 Pa, 500 K) conditions. Structural details are discussed in terms of radial distributions functions, coordination numbers, and instantaneous configurations of the ionic hydration shells. The dynamic properties studied include the velocity autocorrelation functions and self-diffusion coefficients of the ions for both pressure regimes. The results indicate strong changes in the hydration behaviour and mobility of the ions.

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