scholarly journals Chemical Energetics and Atomic Charges Distribution of Variably Sized Hydrated Sulfate Clusters in the light of Density Functional Theory

2021 ◽  
Vol 25 (1) ◽  
pp. 595
Author(s):  
Anant Babu Marahatta
Keyword(s):  
Structural Stability ◽  
Density Functional ◽  
Hydration Number ◽  
Binding Energies ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Atomic Charges ◽  
Electronic Interactions ◽  
Hydrogen Bond Formation ◽  
Depth Analysis

Among the ions classified in the Hofmeister series, the firstly ranked divalent sulfate anion has the strongest hydrating and water-structure making propensity. This unique characteristic actually makes it kosmotropic which causes water molecules to interact each other and contributes to gain structural stability of its hydrated clusters [SO42−(H2O)n]n = 1−40. In this study, few variably sized microhydrated sulfate clusters [SO42−(H2O)n]n = 1−4, 16 are considered separately, and inquired their chemical energetics and atomic charge distributions through ab initio based theoretical model. The main objective of this insight is to specify and interpret their thermodynamic stabilities, binding energies, and specific bonding and electronic interactions quantum mechanically. An in-depth analysis of their change in relative ground state electronic energy with respect to hydration number indicates stronger affinity of the sulfate ion towards water molecules while attaining structural stability in any aqueous type solutions. The mathematically determined values of their binding energy (DE) almost holds up the same with this structural stability order: [SO42−(H2O)16] > [SO42−(H2O)4] > [SO42−(H2O)3] > [SO42−(H2O)2] > [SO42−(H2O)], as reliable as experimentally and molecular dynamics simulation predicted trend. Moreover, the Mulliken derived partial atomic charges feature qualitative charge distribution in them which not only depicts electronic interactions between the specific atoms but also exemplifies the involvement of central sulfate units in hydrogen bond formation with surrounding water molecules.

scholarly journals Aqueous Micro-hydration of Na+(H2O)n=1-7 Clusters: DFT Study

2019 ◽  
Vol 17 (1) ◽  
pp. 260-269 ◽  
Author(s):  
Tahoon M.A. ◽  
Gomaa E.A. ◽  
Suleiman M.H.A.
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Hydration Number ◽  
Sodium Ion ◽  
Water Molecules ◽  
Functional Theory ◽  
Water Binding ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study

AbstractSodium ion micro-solvated clusters, [Na(H2O) n]+, n = 1–7, were completed by (DFT) density functional theory at B3LYP/6-311+G(d,p) level in the gaseous phase. At the ambient situation, the four, five and six micro-solvated configurations can convert from each other. The investigation of the sequential water binding energy on Na+ obviously indicates that the influence of Na+ on the neighboring water molecules goes beyond the first solvation layer with the hydration number of 5. The hydration number of Na+ is 5 and the hydration space (rNa-O) is 2.43 Å. The current study displays that all our simulations have an brilliant harmony with the diffraction result from X-ray scattering study. The vibration frequency of H2O solvent was also determined. This work is important for additional identification of the Na+(H2O)n clusters in aqueous medium.

EFFECTS AND ROLE OF WATER ENVIRONMENT ON A GEMINAL HYDROXYLATED SILICA SURFACE — SELF-CONSISTENT CHARGE DENSITY FUNCTIONAL TIGHT BINDING THEORY BASED MOLECULAR DYNAMICS SIMULATION

2012 ◽  
Vol 11 (01) ◽  
pp. 155-162 ◽  
Author(s):  
Y. L. ZHAO
Keyword(s):  
Hydrogen Bonds ◽  
Charge Density ◽  
Density Functional ◽  
Silica Surface ◽  
Water Environment ◽  
Tight Binding ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Self Consistent ◽  
The Impact

The presence of aqueous solution is inevitable in complex systems involving biological and material components and could affect the interaction between them substantially. To properly simulate such an interaction system, it is necessary to quantitatively explore the effects and specific roles of the water environment on the material surface. In this work, a silica surface was adopted as an example to study the impact of water environment ( 144H2O ) on the structure and energetics using a self-consistent charge density functional tight binding/molecular dynamic method. First, we demonstrated that the silica surface in a vacuum involves a large deformation due to the formation of hydrogen bonds among the surface silanols; in contrast, the deformation is eased in water environment because water molecules could locate in between the silanols and form many hydrogen bonds with the silanols. Therefore, water molecules play an important role to maintain surface from not getting heavily deformed. Our work not only tested the feasible computational methodology of studying nanoscale large systems under water environment at a quantum-mechanical level of theory, but also provided clear evidence on the impact of water environment to the inorganic surface.

scholarly journals Experimental measurements of water molecule binding energies for the second and third solvation shells of [Ca(H 2 O) n ] 2+ complexes

2017 ◽  
Vol 4 (1) ◽  
pp. 160671 ◽  
Author(s):  
E. Bruzzi ◽  
A. J. Stace
Keyword(s):  
Density Functional ◽  
Heat Bath ◽  
Density Functional Theory Calculations ◽  
Solvation Shell ◽  
Binding Energies ◽  
Water Molecules ◽  
Aqueous Environment ◽  
Experimental Measurements ◽  
Similar Data ◽  
Network Of Hydrogen Bonds

Further understanding of the biological role of the Ca 2+ ion in an aqueous environment requires quantitative measurements of both the short- and long-range interactions experienced by the ion in an aqueous medium. Here, we present experimental measurements of binding energies for water molecules occupying the second and, quite possibly, the third solvation shell surrounding a central Ca 2+ ion in [Ca(H 2 O) n ] 2+ complexes. Results for these large, previously inaccessible, complexes have come from the application of finite heat bath theory to kinetic energy measurements following unimolecular decay. Even at n  = 20, the results show water molecules to be more strongly bound to Ca 2+ than would be expected just from the presence of an extended network of hydrogen bonds. For n  > 10, there is very good agreement between the experimental binding energies and recently published density functional theory calculations. Comparisons are made with similar data recorded for [Ca(NH 3 ) n ] 2+ and [Ca(CH 3 OH) n ] 2+ complexes.

Molecular Dynamics Simulation on Aqueous Solution of Calcium Carbonate System

2019 ◽  
Vol 394 ◽  
pp. 73-78
Author(s):  
Da Fang Wang ◽  
Dong Dong Meng ◽  
Feng Jun Wang ◽  
Xin Dong Cui
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Molecular Dynamics Simulation ◽  
Diffusion Coefficients ◽  
Binding Energies ◽  
The Other ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Neutral Surface ◽  
Carbonate System

Molecular dynamics simulation was used to investigate two models of aqueous solution ofcalcium carbonate system between 283K and 373K. The diffusion coefficients of water moleculesdemonstrated that both the electropositive surface (110) on Model-I and neutral surface (104) onModel-II showed interaction with the water molecules, and the surface (110) exhibited strongerelectrostatic interaction with water molecules than the latter, besides obvious anomaly appeared near343K on Model-I. On the other hand, surface (110) exhibited anomalous influences on Ca2+ andCO32- ions near 313K and 343K on Model-I, and only a broad anomaly on CO32- ions near 343K onModel-II. The binding energies between surface (110) / (104) and Ca2+ /CO32- ions demonstrated thatthe surface (104)were more favorable for the growth of the new crystal but weak for the diffusion.

Doping effects on the geometric and electronic structure of tin clusters

2019 ◽  
Vol 21 (44) ◽  
pp. 24478-24488 ◽  
Author(s):  
Martin Gleditzsch ◽  
Marc Jäger ◽  
Lukáš F. Pašteka ◽  
Armin Shayeghi ◽  
Rolf Schäfer
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Density Functional ◽  
Beam Deflection ◽  
Functional Theory ◽  
Doping Effects ◽  
Depth Analysis ◽  
Trajectory Simulations

In depth analysis of doping effects on the geometric and electronic structure of tin clusters via electric beam deflection, numerical trajectory simulations and density functional theory.

A First-Principles Computational Comparison of the Aqueous Anatase TiO2 (001) Interface and the Disordered, Fluorinated TiO2 Interface

2018 ◽  
Author(s):  
Kyle Reeves ◽  
Damien Dambournet ◽  
Christel Laberty-Robert ◽  
Rodolphe Vuilleumier ◽  
Mathieu Salanne
Keyword(s):  
Density Of States ◽  
Density Functional ◽  
Water Dissociation ◽  
Water Molecules ◽  
Chemical Doping ◽  
Charge Balance ◽  
Functional Theory ◽  
Adsorption Of Water ◽  
Properties Of Materials ◽  
Computational Comparison

Chemical doping and other surface modifications have been used to engineer the bulk properties of materials, but their influence on the surface structure and consequently the surface chemistry are often unknown. Previous work has been successful in fluorinating anatase TiO<sub>2</sub> with charge balance achieved via the introduction of Ti vacancies rather than the reduction of Ti. Our work here investigates the interface between this fluorinated titanate with cationic vacancies and a<br>monolayer of water via density functional theory based molecular dynamics. We compute the projected density of states for only those atoms at the interface and for those states that fall within 1eV of the Fermi energy for various steps throughout the simulation, and we determine that the<br>variation in this representation of the density of states serves as a reasonable tool to anticipate where surfaces are most likely to be reactive. In particular, we conclude that water dissociation at the surface is the main mechanism that influences the anatase (001) surface whereas the change in<br>the density of states at the surface of the fluorinated structure is influenced primarily through the adsorption of water molecules at the surface.

A First-Principles Computational Comparison of the Aqueous Anatase TiO2 (001) Interface and the Disordered, Fluorinated TiO2 Interface

2018 ◽  
Author(s):  
Kyle Reeves ◽  
Damien Dambournet ◽  
Christel Laberty-Robert ◽  
Rodolphe Vuilleumier ◽  
Mathieu Salanne
Keyword(s):  
Density Of States ◽  
Density Functional ◽  
Water Dissociation ◽  
Water Molecules ◽  
Chemical Doping ◽  
Charge Balance ◽  
Functional Theory ◽  
Adsorption Of Water ◽  
Properties Of Materials ◽  
Computational Comparison

Chemical doping and other surface modifications have been used to engineer the bulk properties of materials, but their influence on the surface structure and consequently the surface chemistry are often unknown. Previous work has been successful in fluorinating anatase TiO<sub>2</sub> with charge balance achieved via the introduction of Ti vacancies rather than the reduction of Ti. Our work here investigates the interface between this fluorinated titanate with cationic vacancies and a<br>monolayer of water via density functional theory based molecular dynamics. We compute the projected density of states for only those atoms at the interface and for those states that fall within 1eV of the Fermi energy for various steps throughout the simulation, and we determine that the<br>variation in this representation of the density of states serves as a reasonable tool to anticipate where surfaces are most likely to be reactive. In particular, we conclude that water dissociation at the surface is the main mechanism that influences the anatase (001) surface whereas the change in<br>the density of states at the surface of the fluorinated structure is influenced primarily through the adsorption of water molecules at the surface.

QM/MM Simulations of Organic Phosphorus Adsorption at the Diaspore-Water Interface

2019 ◽  
Author(s):  
Prasanth Babu Ganta ◽  
Oliver Kühn ◽  
Ashour Ahmed
Keyword(s):  
Interaction Energy ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Water Interface ◽  
Mineral Surfaces ◽  
Soil Mineral ◽  
Phosphorus Adsorption ◽  
Covalent Bonds ◽  
Binding Mechanisms

The phosphorus (P) immobilization and thus its availability for plants are mainly affected by the strong interaction of phosphates with soil components especially soil mineral surfaces. Related reactions have been studied extensively via sorption experiments especially by carrying out adsorption of ortho-phosphate onto Fe-oxide surfaces. But a molecular-level understanding for the P-binding mechanisms at the mineral-water interface is still lacking, especially for forest eco-systems. Therefore, the current contribution provides an investigation of the molecular binding mechanisms for two abundant phosphates in forest soils, inositol hexaphosphate (IHP) and glycerolphosphate (GP), at the diaspore mineral surface. Here a hybrid electrostatic embedding quantum mechanics/molecular mechanics (QM/MM) based molecular dynamics simulation has been applied to explore the diaspore-IHP/GP-water interactions. The results provide evidence for the formation of different P-diaspore binding motifs involving monodentate (M) and bidentate (B) for GP and two (2M) as well as three (3M) monodentate for IHP. The interaction energy results indicated the abundance of the GP B motif compared to the M one. The IHP 3M motif has a higher total interaction energy compared to its 2M motif, but exhibits a lower interaction energy per bond. Compared to GP, IHP exhibited stronger interaction with the surface as well as with water. Water was found to play an important role in controlling these diaspore-IHP/GP-water interactions. The interfacial water molecules form moderately strong H-bonds (HBs) with GP and IHP as well as with the diaspore surface. For all the diaspore-IHP/GP-water complexes, the interaction of water with diaspore exceeds that with the studied phosphates. Furthermore, some water molecules form covalent bonds with diaspore Al atoms while others dissociate at the surface to protons and hydroxyl groups leading to proton transfer processes. Finally, the current results confirm previous experimental conclusions indicating the importance of the number of phosphate groups, HBs, and proton transfers in controlling the P-binding at soil mineral surfaces.

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