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 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.

scholarly journals Icephobicity of Functionalized Graphene Surfaces

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Xiang-Xiong Zhang ◽  
Min Chen
Keyword(s):  
Molecular Dynamics ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Chloride Ions ◽  
Water Molecules ◽  
Sodium Ions ◽  
Functionalized Graphene ◽  
Functionalized Surfaces ◽  
The Difference ◽  
Dynamics Simulations

Manipulating the ice nucleation ability of liquid water by solid surface is of fundamental importance, especially in the design of icephobic surfaces. In this paper, the icephobicity of graphene surfaces functionalized by sodium ions, chloride ions, or methane molecules is investigated using molecular dynamics simulations. The icephobicity of the surface is evaluated by the freezing temperature. The freezing temperature on surface functionalized by methane molecules decreases at first and then increases as a function of the number groups, while the freezing temperature increases monotonically as a function of the number groups upon surfaces functionalized by sodium ions or chloride ions. The difference can be partially explained by the potential morphologies near the surfaces. Additionally, the validity of indicating the ice nucleation ability of water molecules using the number of six rings in the system is examined. Current study shows that the ice nucleation upon functionalized surfaces is inhibited when compared with smooth graphene substrate, which proves the feasibility of changing the icephobicity of the surfaces by functionalizing with certain ions or molecules.

A Molecular Dynamics Study of Aqueous Solutions I. First Results for LiCl in H2O

1974 ◽  
Vol 29 (8) ◽  
pp. 1164-1171 ◽  
Author(s):  
K. Heinzinger ◽  
P. C. Vogel
Keyword(s):  
Molecular Dynamics ◽  
Neutron Diffraction ◽  
Chloride Ions ◽  
Water Molecules ◽  
Kinetic Properties ◽  
Static Properties ◽  
Lithium Ions ◽  
X Ray ◽  
Hydration Shells ◽  
First Results

First results of a molecular dynamics study of an aqueous LiCl solution are reported. The system investigated consisted of 216 particles, 198 water molecules, 9 lithium ions, and 9 chloride ions. The calculations lead to fair agreement with the static properties of the first hydration shells of the ions as derived from X-ray and neutron diffraction studies, and with kinetic properties as derived from NMR measurements. A model for the motion of the water molecules in the first hydration sphere of Li+ is tentatively proposed.

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 Aqueous Solutions II. Cesium Chloride in H2O

1975 ◽  
Vol 30 (6-7) ◽  
pp. 789-796 ◽  
Author(s):  
P. C. Vogel ◽  
K. Heinzinger
Keyword(s):  
Molecular Dynamics ◽  
Elevated Temperatures ◽  
Pure Water ◽  
Pair Correlation ◽  
Cesium Chloride ◽  
Pair Interaction ◽  
Chloride Ions ◽  
Water Molecules ◽  
Static Properties ◽  
Average Potential Energy

Abstract Results of a molecular dynamics study of an aqueous CsCl solution are reported. The system consisted of 216 particles, 200 water molecules, 8 cesium ions and 8 chloride ions and was run over 8000 time steps equivalent of 9 · 10-13 sec. On the basis of radial pair correlation functions, average potential energy of the water molecules and pair interaction energy distribution the static properties of the first hydration shells of the ions are discussed in detail. The self diffusion coefficient for the water molecules is calculated and compared with NMR measurement as well as with molecular dynamics calculations for pure water at elevated temperatures and pressures.

Sign in / Sign up

Export Citation Format

Share Document