Molecular Dynamics Study of an Aqueous LiF Solution

1991 ◽  
Vol 46 (3) ◽  
pp. 221-228 ◽  
Author(s):  
Sheng-Bai Zhu ◽  
G. Wilse Robinson
Keyword(s):  
Molecular Dynamics ◽  
Close Contact ◽  
Water Structure ◽  
Water Model ◽  
Pure Liquid ◽  
Surrounding Water ◽  
Hydration Shells ◽  
Complete Breakdown ◽  
Solvent Molecules ◽  
Dynamics Simulations

AbstractThe structure and properties of a 1.791 molal aqueous LiF solution is investigated by performing molecular dynamics simulations using a water model with both bond flexibility and instantaneously responsive polarization. On average, each cation is in close contact with about one anion. This causes a strong overlap of the hydration shells and an almost complete breakdown of the surrounding water structure. While the lone pairs of the hydration waters in the first Li+ shell occupy preferentially tetrahedral positions, the orientational distribution of the solvent molecules around F--is quite uniform. By comparing various autocorrelation functions of water molecules in the solution and in the pure liquid, the influence of solvated ions on the translational, rotational and vibrational motions of hydration water can be studied

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 Origin and control of ionic hydration patterns in nanopores

2020 ◽  
Author(s):  
Miraslau Barabash ◽  
William Gibby ◽  
Carlo Guardiani ◽  
Alex Smolyanitsky ◽  
Dmitry Luchinsky ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Water Molecules ◽  
Complex Interplay ◽  
Surrounding Water ◽  
Ionic Hydration ◽  
Hydration Shells ◽  
Water Layers ◽  
Dynamics Simulations ◽  
And Control

Abstract In 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. We now address the questions of 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 terms of experimentally accessible radial distributions functions, yielding results that agree well with molecular dynamics simulations. We show that the patterns are attributable to a complex interplay of ionic hydration shells with water layers adjacent to the 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 Combined Use of Structure Analysis, Studies of Molecular Association in Solution, and Molecular Modelling to Understand the Different Propensities of Dihydroxybenzoic Acids to Form Solid Phases

Pharmaceutics ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 734
Author(s):  
Aija Trimdale ◽  
Anatoly Mishnev ◽  
Agris Bērziņš
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Molecular Association ◽  
Hydroxyl Groups ◽  
Solid Phases ◽  
Solvent Molecules ◽  
Dynamics Simulations

The arrangement of hydroxyl groups in the benzene ring has a significant effect on the propensity of dihydroxybenzoic acids (diOHBAs) to form different solid phases when crystallized from solution. All six diOHBAs were categorized into distinctive groups according to the solid phases obtained when crystallized from selected solvents. A combined study using crystal structure and molecule electrostatic potential surface analysis, as well as an exploration of molecular association in solution using spectroscopic methods and molecular dynamics simulations were used to determine the possible mechanism of how the location of the phenolic hydroxyl groups affect the diversity of solid phases formed by the diOHBAs. The crystal structure analysis showed that classical carboxylic acid homodimers and ring-like hydrogen bond motifs consisting of six diOHBA molecules are prominently present in almost all analyzed crystal structures. Both experimental spectroscopic investigations and molecular dynamics simulations indicated that the extent of intramolecular bonding between carboxyl and hydroxyl groups in solution has the most significant impact on the solid phases formed by the diOHBAs. Additionally, the extent of hydrogen bonding with solvent molecules and the mean lifetime of solute–solvent associates formed by diOHBAs and 2-propanol were also investigated.

scholarly journals Three- and Four-Site Models for Heavy Water: SPC/E-HW, TIP3P-HW, and TIP4P/2005-HW

2021 ◽  
Author(s):  
Johanna-Barbara Linse ◽  
Jochen S. Hub
Keyword(s):  
Molecular Dynamics ◽  
Heavy Water ◽  
Room Temperature ◽  
Deuterium Oxide ◽  
Water Structure ◽  
Light Water ◽  
Pair Potentials ◽  
Effective Pair ◽  
Water Models ◽  
Dynamics Simulations

Heavy water or deuterium oxide, D<sub>2</sub>O, is used as solvent in various biophysical and chemical experiments. To model such experiments with molecular dynamics simulations, effective pair potentials for heavy water are required that reproduce the well-known physicochemical differences relative to light water. We present three effective pair potentials for heavy water, denoted SPC/E-HW, TIP3P-HW, and TIP4P/2005-HW. The models were parametrized by modifying widely used three- and four-site models for light water, with aim of maintaining the specific characteristics of the light water models. At room temperature, the SPC/E-HW and TIP3P-HW capture the modulations relative to light water of the mass and electron densities, heat of vaporization, diffusion coefficient, and water structure. TIP4P/2005-HW captures in addition the density of heavy water over a wide temperature range.

scholarly journals Three- and Four-Site Models for Heavy Water: SPC/E-HW, TIP3P-HW, and TIP4P/2005-HW

2021 ◽  
Author(s):  
Johanna-Barbara Linse ◽  
Jochen S. Hub
Keyword(s):  
Molecular Dynamics ◽  
Heavy Water ◽  
Room Temperature ◽  
Deuterium Oxide ◽  
Water Structure ◽  
Light Water ◽  
Pair Potentials ◽  
Effective Pair ◽  
Water Models ◽  
Dynamics Simulations

Heavy water or deuterium oxide, D<sub>2</sub>O, is used as solvent in various biophysical and chemical experiments. To model such experiments with molecular dynamics simulations, effective pair potentials for heavy water are required that reproduce the well-known physicochemical differences relative to light water. We present three effective pair potentials for heavy water, denoted SPC/E-HW, TIP3P-HW, and TIP4P/2005-HW. The models were parametrized by modifying widely used three- and four-site models for light water, with aim of maintaining the specific characteristics of the light water models. At room temperature, the SPC/E-HW and TIP3P-HW capture the modulations relative to light water of the mass and electron densities, heat of vaporization, diffusion coefficient, and water structure. TIP4P/2005-HW captures in addition the density of heavy water over a wide temperature range.

scholarly journals Lauryl Phosphate Flotation Chemistry in Barite Flotation

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 280
Author(s):  
Ying Lu ◽  
Weiping Liu ◽  
Xuming Wang ◽  
Huaigang Cheng ◽  
Fangqin Cheng ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Froth Flotation ◽  
Contrast Material ◽  
Water Structure ◽  
Phosphate Adsorption ◽  
Oil Well ◽  
Wide Ph Range ◽  
Interfacial Water Structure ◽  
Dynamics Simulations

Barite has numerous applications including barium mud for oil well drilling, manufacture of elemental barium, filler for paper and rubber industries, and contrast material for X-ray radiology for the digestive system. Currently, froth flotation is the main method for the beneficiation of barite using fatty acid as a typical collector. In this research, it was found that lauryl phosphate is also a promising collector for barite flotation. Results from microflotation, contact angle, and zeta potential indicate that lauryl phosphate is adsorbed on the barite surface and thus achieves superior flotation efficiency at a wide pH range. The interfacial water structure and wetting characteristics of barite surface with/without lauryl phosphate adsorption were also evaluated by molecular dynamics simulations (MDS). The results from molecular dynamics simulations and interaction energy calculations are in accord with the experimental results, which suggest that lauryl phosphate might be a potential collector for the flotation of barite.

scholarly journals Thermodynamic Study of Hydrolysis Reactions in Aqueous Solution fromAb InitioPotential and Molecular Dynamics Simulations

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
S. Tolosa ◽  
A. Hidalgo ◽  
J. A. Sansón
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Free Energy ◽  
Reaction Mechanism ◽  
Molecular Dynamics Simulations ◽  
Infinite Dilution ◽  
Theoretical Study ◽  
Water Model ◽  
Dynamics Simulations ◽  
Hydrolysis Of

A procedure for the theoretical study of chemical reactions in solution by means of molecular dynamics simulations of aqueous solution at infinite dilution is described usingab initiosolute-solvent potentials and TIP3P water model to describe the interactions. The procedure is applied to the study of neutral hydrolysis of various molecules (HCONH2, HNCO, HCNHNH2, and HCOOCH3) via concerted and water-assisted mechanisms. We used the solvent as a reaction coordinate and the free energy curves for the calculation of the properties related with the reaction mechanism, namely, reaction and activation energies.

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