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 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.

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.

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 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.

scholarly journals Molecular Dynamics Modellization and Simulation of Water Diffusion through Plant Cutin

1999 ◽  
Vol 54 (11) ◽  
pp. 896-902 ◽  
Author(s):  
Antonio Matas ◽  
Antonio Heredia
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Structural Information ◽  
Md Simulations ◽  
Water Molecules ◽  
Plant Cuticle ◽  
X Ray Diffraction ◽  
Cross Link ◽  
X Ray ◽  
Good Agreement

Abstract A theoretical molecular modelling study has been conducted for cutin, the biopolyester that forms the main structural component of the plant cuticle. Molecular dynamics (MD) simulations, extended over several ten picoseconds, suggests that cutin is a moderately flexible netting with motional constraints mainly located at the cross-link sites of functional ester groups. This study also gives structural information essentially in accordance with previously reported experimental data, obtained from X -ray diffraction and nuclear magnetic resonance experiments. MD calculations were also performed to simulate the diffusion of water mole­cules through the cutin biopolymer. The theoretical analysis gives evidence that water perme­ation proceedes by a “hopping mechanism”. Coefficients for the diffusion of the water molecules in cutin were obtained from their mean-square displacements yielding values in good agreement with experimental data.

A single crystal X-ray study of a sulphate-bearing buttgenbachite, Cu36Cl7.8(NO3)1.3(SO4)0.35(OH)62.2.5.2H2O, and a re-examination of the crystal chemistry of the buttgenbachite-connellite series

2003 ◽  
Vol 67 (1) ◽  
pp. 47-60 ◽  
Author(s):  
D. E. Hibbs ◽  
P. Leverett ◽  
P. A. Williams
Keyword(s):  
Single Crystal ◽  
Democratic Republic ◽  
Democratic Republic Of Congo ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Water Molecules ◽  
Data Set ◽  
X Ray ◽  
Positional Disorder ◽  
Anion Substitution

AbstractThe single-crystal X-ray structure of a sulphate-bearing buttgenbachite, Cu36Cl7.8(NO3)1.3(SO4)0.35(OH)62.2.5.2H2O, from Likasi, Democratic Republic of Congo, has been determined at 100 and 288 K. The basic framework of the structure is the same as has been previously reported for buttgenbachite, except for the identification of a hydrogen-bonded chloride ion (occupancy 0.6) at the origin instead of a Cu ion with partial occupancy. The nature of nitrate positional disorder along channels in the c direction and how this relates to the presence of other species such as chloride ions and water molecules and, most importantly, sulphate ions has been elucidated. One nitrate ion, with an occupancy of 0.18, lies at 2/3,l/3,l/4 and shares the site with a chloride ion (occupancy 0.30) and also a sulphate ion (occupancy 0.09); a second nitrate, with an occupancy of 0.24, lies at 2/3,1/3,0.084 and shares the site with a water molecule (occupancy 0.06). As a result, a formula of Cu36Cl7.8(NO3)1.3(SO4)0.35(OH)62.2.5.2H2O is obtained. Re-refinement of deposited data for a supposed connellite crystal from the Toughnut mine,Tombstone, Arizona gives a related, but different, pattern of anion substitution. No sulphate could be detected in the structure and it is evident that this structure refers to buttgenbachite. A nitrate nitrogen atom and a chloride ion are disordered at 2/3,l/3,l/4, the overall site being fully occupied. A chloride ion with ∼0.5 occupancy is sited at the origin and the formula Cu36Cl7.9(NO3)1.1(OH)63.4H2O is indicated. Re-refinement of a deposited data set for another buttgenbachite crystal from the Likasi mine reveals a partially occupied nitrate centred at 2/3,l/3, z and a partially occupied chloride at 2/3,l/3,l/4. Either 0.5Cl–, OH–, H2O or H3O+ is located at the origin. If the latter is the case, the stoichiometry for this buttgenbachite is Cu36Cl6.5(NO3)1.5(OH)64.5.5H2O. The present study has highlighted the fact that a range of compositions for buttgenbachite exists, depending on the pH and relative activities of chloride, nitrate and sulphate ions in solutions from which the mineral crystallizes.

X-ray Diffraction Studies on Supercooled Aqueous Lithium Bromide and Lithium Iodide Solutions

1997 ◽  
Vol 52 (6-7) ◽  
pp. 521-527 ◽  
Author(s):  
Toshiyuki Takamuku ◽  
Motoyuki Yamagami ◽  
Hisanobu Wakita ◽  
Toshio Yamaguchi
Keyword(s):  
Hydration Shell ◽  
Lithium Bromide ◽  
Distribution Functions ◽  
Halide Ions ◽  
X Ray Diffraction ◽  
Lithium Ions ◽  
X Ray ◽  
Hydration Shells ◽  
Effects Of Temperature ◽  
Aqueous Lithium Bromide

Abstract X-ray diffraction measurements were performed on liquid LiBr • 5H2O and Lil • 5H2O at temperatures from -30 to 25 °C. The total radial distribution functions did show that on supercooling the hydration shell of the halide ions becomes more structured, while that of the lithium ions becomes distorted. The larger the halide ion, the stronger becomes the water-water interaction around halide ions with lowering temperature. However, the distance between the water molecules in the hydration shells of the halide ions depends little on their size. On the basis of the present results, together with those of our previous investigation on LiCl • 5H2O at temperatures from - 135 to 100°C, the effects of temperature and the size of the halide ions on the structure of the solution are discussed.

About the degree of hydration in potassiumtrisoxalatochromate hydrate

2005 ◽  
Vol 220 (11) ◽  
Author(s):  
Chunhua Hu ◽  
Gernot Heger ◽  
Irmgard Kalf ◽  
Ullrich Englert
Keyword(s):  
Neutron Diffraction ◽  
Water Molecules ◽  
Structure Model ◽  
Hydrogen Atoms ◽  
Neutron Data ◽  
X Ray ◽  
Degree Of Hydration ◽  
Thermogravimetric Data ◽  
Hydration Model ◽  
Good Agreement

AbstractData obtained from single crystal X-ray and neutron diffraction experiments have been combined with results from thermogravimetry in order to derive an improved structure model for potassium tris(oxalato)chromate hydrate. The degree of hydration for this compound has been reinvestigated: Earlier work assumed a trihydrate stoichiometry and had to accept an unusually short K···O distance of 2.3 Å. Our neutron data reveal the position of the hydrogen atoms in the water molecules; they prove that abnormally short separations between a cation and atoms of a water molecule can only occur between sites of mutually exclusive occupancy and hence remain without chemical relevance. Closest K···O distances in our revised hydration model amount to 2.6 Å, in good agreement with expectation. Both diffraction experiments and thermogravimetric data agree with the stoichiometry K

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.

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