Hydration structure of Na+, K+, F−, and Cl− in ambient and supercritical water: A quantum mechanics/molecular mechanics study

Ma, Haibo

doi:10.1002/qua.24597

Cited by 23 publications

(7 citation statements)

References 48 publications

(71 reference statements)

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“…The RDF of Cl···H OH and Cl···H w of Kao-CaCl 2 and Kao-NaCl (Figure ) clearly demonstrates that Cl – anions can interact with both water molecules and the kaolinite hydroxylated surface through weak hydrogen bonding. The HB distance is about 2.25 Å which is consistent with previous computational and experimental studies. − This is the possible reason why the number of hydrogen bonds at the kaolinite hydroxylated surface slightly decreases in the presence of Cl – anions.…”

Section: Hydrogen Bonds Between Water and The Clay Surfacesupporting

confidence: 90%

Surface Wettability of Basal Surfaces of Clay Minerals: Insights from Molecular Dynamics Simulation

et al. 2016

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Understanding the wettability of clay mineral surfaces is crucial for enhancing oil recovery, investigating primary migration of hydrocarbon, and evaluating the performance of sealing rocks in a petroleum system. On the basis of molecular dynamics simulations, we investigated the interactions between four typical clay minerals (i.e., pyrophyllite, montmorillonite, illite, and kaolinite) and confined pore fluids (i.e., water/alkane/salts). The influences of surface group, layer charge, and salts on the wettability of clay surfaces were revealed. As the layer charge increases, the hydrophilicity of the montmorillonite basal surface gradually increases. The basal surface of 2:1-type pyrophyllite is completely alkane-wet independent of salts. However, for 1:1-type kaolinite, the presence of salts makes the siloxane surface completely water-wet, whereas it is partially alkane-wet at the absence of salts. In general, the salt ions adsorbed onto clay surfaces promote the surface hydrophilicity. By using nonequilibrium molecular dynamics, we explored the hydrodynamics of the water/alkane/salts fluid confined in slit nanopores with pore walls made up of montmorillonite and kaolinite. Both montmorillonite and kaolinite surfaces remarkably restrain the movement of the water confined in nanopores. Decane molecules tend to aggregate together and transport as a cluster. Moreover, the migration of the decane cluster is faster than that of water molecules. These findings are helpful for understanding the primary migration of hydrocarbon in clayey source rocks and the geological sealing of oil by clayey cap rocks in petroleum systems.

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Section: Hydrogen Bonds Between Water and The Clay Surfacesupporting

confidence: 90%

Surface Wettability of Basal Surfaces of Clay Minerals: Insights from Molecular Dynamics Simulation

et al. 2016

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“…Its n values agree well with those from other simulations that use either the SAHB method but a different ion force field, 39 for which F − to I − are 6.1, 6.9, 7.5, and 7.6, or that use the GC method based on g(r XH ) 60,68 whose n values are 6.2-6.5 for F − and 7.0-7.4 for Cl − . GC n values obtained from g(r XH ) by neutron diffraction 8,45,54,69 are also close at 6.…”

Section: Resultssupporting

confidence: 77%

Instantaneous, parameter-free methods to define a solute’s hydration shell

Chatterjee

Higham

Henchman

2015

The Journal of Chemical Physics

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Modeling the hydration of mono-atomic anions from the gas phase to the bulk phase: The case of the halide Instantaneous, parameter-free methods to define a solute's hydration shell A range of methods are presented to calculate a solute's hydration shell from computer simulations of dilute solutions of monatomic ions and noble gas atoms. The methods are designed to be parameter-free and instantaneous so as to make them more general, accurate, and consequently applicable to disordered systems. One method is a modified nearest-neighbor method, another considers solute-water Lennard-Jones overlap followed by hydrogen-bond rearrangement, while three methods compare various combinations of water-solute and water-water forces. The methods are tested on a series of monatomic ions and solutes and compared with the values from cutoffs in the radial distribution function, the nearest-neighbor distribution functions, and the strongest-acceptor hydrogen bond definition for anions. The Lennard-Jones overlap method and one of the force-comparison methods are found to give a hydration shell for cations which is in reasonable agreement with that using a cutoff in the radial distribution function. Further modifications would be required, though, to make them capture the neighboring water molecules of noble-gas solutes if these weakly interacting molecules are considered to constitute the hydration shell. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.[http://dx

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“…In particular, at comparable sizes, anions induce a more pronounced perturbation of their hydration shells compared to cations, because they are hydrogen-bond acceptors. 17,50,113,268,282,294,[296][297][298][299][300][301][302] The same applies to small or/and multivalent ions, because they generate a stronger electric field at their surface. This more important perturbation may require the inclusion of the second hydration shell into the QM region.…”

Section: Discussionmentioning

confidence: 96%

Absolute proton hydration free energy, surface potential of water, and redox potential of the hydrogen electrode from first principles: QM/MM MD free-energy simulations of sodium and potassium hydration

Hofer

Hünenberger

2018

The Journal of Chemical Physics

104

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The absolute intrinsic hydration free energy G • H + ,wat of the proton, the surface electric potential jump χ • wat upon entering bulk water, and the absolute redox potential V • H + ,wat of the reference hydrogen electrode are cornerstone quantities for formulating single-ion thermodynamics on absolute scales. They can be easily calculated from each other but remain fundamentally elusive, i.e., they cannot be determined experimentally without invoking some extra-thermodynamic assumption (ETA). The Born model provides a natural framework to formulate such an assumption (Born ETA), as it automatically factors out the contribution of crossing the water surface from the hydration free energy. However, this model describes the short-range solvation inaccurately and relies on the choice of arbitrary ion-size parameters. In the present study, both shortcomings are alleviated by performing first-principle calculations of the hydration free energies of the sodium (Na + ) and potassium (K + ) ions. The calculations rely on thermodynamic integration based on quantum-mechanical molecular-mechanical (QM/MM) molecular dynamics (MD) simulations involving the ion and 2000 water molecules. The ion and its first hydration shell are described using a correlated ab initio method, namely resolution-of-identity second-order Møller-Plesset perturbation (RIMP2). The next hydration shells are described using the extended simple point charge water model (SPC/E). The hydration free energy is first calculated at the MM level and subsequently increased by a quantization term accounting for the transformation to a QM/MM description. It is also corrected for finite-size, approximate-electrostatics, and potentialsummation errors, as well as standard-state definition. These computationally intensive simulations provide accurate first-principle estimates for G • H + ,wat , χ • wat , and V • H + ,wat , reported with statistical errors based on a confidence interval of 99%. The values obtained from the independent Na + and K + simulations are in excellent agreement. In particular, the difference between the two hydration free energies, which is not an elusive quantity, is 73.9 ± 5.4 kJ mol 1 (K + minus Na + ), to be compared with the experimental value of 71.7 ± 2.8 kJ mol 1 . The calculated values of G • H + ,wat , χ • wat , and V • H + ,wat ( 1096.7 ± 6.1 kJ mol 1 , 0.10 ± 0.10 V, and 4.32 ± 0.06 V, respectively, averaging over the two ions) are also in remarkable agreement with the values recommended by Reif and Hünenberger based on a thorough analysis of the experimental literature ( 1100 ± 5 kJ mol 1 , 0.13 ± 0.10 V, and 4.28 ± 0.13 V, respectively). The QM/MM MD simulations are also shown to provide an accurate description of the hydration structure, dynamics, and energetics. Published by AIP Publishing.

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Hydration structure of Na⁺, K⁺, F⁻, and Cl⁻ in ambient and supercritical water: A quantum mechanics/molecular mechanics study

Cited by 23 publications

References 48 publications

Surface Wettability of Basal Surfaces of Clay Minerals: Insights from Molecular Dynamics Simulation

Surface Wettability of Basal Surfaces of Clay Minerals: Insights from Molecular Dynamics Simulation

Instantaneous, parameter-free methods to define a solute’s hydration shell

Absolute proton hydration free energy, surface potential of water, and redox potential of the hydrogen electrode from first principles: QM/MM MD free-energy simulations of sodium and potassium hydration

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