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Bone RA, Chung MKJ, Ponder JW, Riccardi D, Muzny C, Sundararaman R, Schwarz K. A new method to calculate broadband dielectric spectra of solvents from molecular dynamics simulations demonstrated with polarizable force fields. J Chem Phys 2024; 161:064306. [PMID: 39132799 PMCID: PMC11324330 DOI: 10.1063/5.0217883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Accepted: 07/26/2024] [Indexed: 08/13/2024] Open
Abstract
Simulating the dielectric spectra of solvents requires the nuanced definition of inter- and intra-molecular forces. Non-polarizable force fields, while thoroughly benchmarked for dielectric applications, do not capture all the spectral features of solvents, such as water. Conversely, polarizable force fields have been largely untested in the context of dielectric spectroscopy but include charge and dipole fluctuations that contribute to intermolecular interactions. We benchmark non-polarizable force fields and the polarizable force fields AMOEBA03 and HIPPO for liquid water and find that the polarizable force fields can capture all the experimentally observed spectral features with varying degrees of accuracy. However, the non-polarizable force fields miss at least one peak. To diagnose this deficiency, we decompose the liquid water spectra from polarizable force fields at multiple temperatures into static and induced dipole contributions and find that the peak originates from induced dipole contributions. Broadening our inquiry to other solvents parameterized with the AMOEBA09 force field, we demonstrate good agreement between the experimental and simulated dielectric spectra of methanol and formamide. To produce these spectra, we develop a new computational approach to calculate the dielectric spectrum via the fluctuation dissipation theorem. This method minimizes the error in both the low and high frequency portions of the spectrum, improving the overall accuracy of the simulated spectrum and broadening the computed frequency range.
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Affiliation(s)
| | - Moses K. J. Chung
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, USA
| | - Jay W. Ponder
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, USA
| | - Demian Riccardi
- Material Measurement Laboratory, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Chris Muzny
- Material Measurement Laboratory, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Ravishankar Sundararaman
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 8th St., Troy, New York 12180, USA
| | - Kathleen Schwarz
- Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Dr., Gaithersburg, Maryland 20899, USA
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2
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Elliott GR, Wanless EJ, Webber GB, Andersson GG, Craig VSJ, Page AJ. Dynamic Ion Correlations and Ion-Pair Lifetimes in Aqueous Alkali Metal Chloride Electrolytes. J Phys Chem B 2024; 128:7438-7444. [PMID: 39037039 DOI: 10.1021/acs.jpcb.4c01992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2024]
Abstract
Electrolytes are central to many technological applications, as well as life itself. The behavior and properties of electrolytes are often described in terms of ion pairs, whereby ions associate as either contact ion pairs (in which ions are "touching") solvent-separated ion pairs (in which ions' solvent shells overlap) or solvent-solvent-separated ion pairs (in which ions' solvent shells are distinct). However, this paradigm is generally restricted to statistically averaged descriptions of solution structure and ignores temporal behavior. Here we elucidate the time-resolved dynamics of these ion-ion interactions in aqueous metal chloride electrolytes using the partial van Hove correlation function, based on polarizable molecular dynamics simulations. Our results show that the existence and persistence of ion pairs in aqueous metal chloride electrolytes should not be assumed a priori, but in fact are ion specific features of the solution with lifetimes on subpicosecond time scales.
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Affiliation(s)
- Gareth R Elliott
- Discipline of Chemistry, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Erica J Wanless
- Discipline of Chemistry, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Grant B Webber
- Discipline of Chemical Engineering, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Gunther G Andersson
- Flinders Institute of Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Adelaide, South Australia 5042, Australia
| | - Vincent S J Craig
- Department of Material Physics, Research School of Physics, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Alister J Page
- Discipline of Chemistry, The University of Newcastle, Callaghan, New South Wales 2308, Australia
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3
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Pireddu G, Fairchild CJ, Niblett SP, Cox SJ, Rotenberg B. Impedance of nanocapacitors from molecular simulations to understand the dynamics of confined electrolytes. Proc Natl Acad Sci U S A 2024; 121:e2318157121. [PMID: 38662549 PMCID: PMC11067016 DOI: 10.1073/pnas.2318157121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 04/01/2024] [Indexed: 05/05/2024] Open
Abstract
Nanoelectrochemical devices have become a promising candidate technology across various applications, including sensing and energy storage, and provide new platforms for studying fundamental properties of electrode/electrolyte interfaces. In this work, we employ constant-potential molecular dynamics simulations to investigate the impedance of gold-aqueous electrolyte nanocapacitors, exploiting a recently introduced fluctuation-dissipation relation. In particular, we relate the frequency-dependent impedance of these nanocapacitors to the complex conductivity of the bulk electrolyte in different regimes, and use this connection to design simple but accurate equivalent circuit models. We show that the electrode/electrolyte interfacial contribution is essentially capacitive and that the electrolyte response is bulk-like even when the interelectrode distance is only a few nanometers, provided that the latter is sufficiently large compared to the Debye screening length. We extensively compare our simulation results with spectroscopy experiments and predictions from analytical theories. In contrast to experiments, direct access in simulations to the ionic and solvent contributions to the polarization allows us to highlight their significant and persistent anticorrelation and to investigate the microscopic origin of the timescales observed in the impedance spectrum. This work opens avenues for the molecular interpretation of impedance measurements, and offers valuable contributions for future developments of accurate coarse-grained representations of confined electrolytes.
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Affiliation(s)
- Giovanni Pireddu
- Physico-Chimie des Électrolytes et Nanosystèmes Interfaciaux, CNRS, Sorbonne Université, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux (PHENIX), CNRS, Sorbonne Université, ParisF-75005, France
| | - Connie J. Fairchild
- Yusuf Hamied Department of Chemistry, University of Cambridge, CambridgeCB2 1EW, United Kingdom
| | - Samuel P. Niblett
- Yusuf Hamied Department of Chemistry, University of Cambridge, CambridgeCB2 1EW, United Kingdom
| | - Stephen J. Cox
- Yusuf Hamied Department of Chemistry, University of Cambridge, CambridgeCB2 1EW, United Kingdom
| | - Benjamin Rotenberg
- Physico-Chimie des Électrolytes et Nanosystèmes Interfaciaux, CNRS, Sorbonne Université, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux (PHENIX), CNRS, Sorbonne Université, ParisF-75005, France
- Réseau sur le Stockage Electrochimique de l’Energie, Fédération de Recherche CNRS 3459, Amiens Cedex80039, France
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4
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Naseri Boroujeni S, Maribo-Mogensen B, Liang X, Kontogeorgis GM. Theoretical and practical investigation of ion-ion association in electrolyte solutions. J Chem Phys 2024; 160:154509. [PMID: 38639315 DOI: 10.1063/5.0198308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 03/26/2024] [Indexed: 04/20/2024] Open
Abstract
In this study, we present a new equation of state for electrolyte solutions, integrating the statistical associating fluid theory for variable range interactions utilizing the generic Mie form and binding Debye-Hückel theories. This equation of state underscores the pivotal role of ion-ion association in determining the properties of electrolyte solutions. We propose a unified framework that simultaneously examines the thermodynamic properties of electrolyte solutions and their electrical conductivity, given the profound impact of ion pairing on this transport property. Using this equation of state, we predict the liquid density, mean ionic activity coefficient, and osmotic coefficient for binary NaCl, Na2SO4, and MgSO4 aqueous solutions at 298.15 K. Additionally, we evaluate the molar conductivity of these systems by considering the fraction of free ions derived from our equation of state in conjunction with two advanced electrical conductivity models. Our results reveal that, while ion-ion association has a minimal influence on the modification of the predicted properties of sodium chloride solutions, their impact on sodium and magnesium sulfate solutions is considerably more noticeable.
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Affiliation(s)
- Saman Naseri Boroujeni
- Center for Energy Resources Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark (DTU), Søltofts Plads, Building 229, 2800 Kgs. Lyngby, Denmark
| | - B Maribo-Mogensen
- Hafnium Labs ApS., Vestergade 16, 3rd floor, 1456 Copenhagen, Denmark
| | - X Liang
- Center for Energy Resources Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark (DTU), Søltofts Plads, Building 229, 2800 Kgs. Lyngby, Denmark
| | - G M Kontogeorgis
- Center for Energy Resources Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark (DTU), Søltofts Plads, Building 229, 2800 Kgs. Lyngby, Denmark
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5
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Jeon J, Cho M. Dielectric Response and Linear Absorption Spectroscopy of Ionic Systems. J Chem Theory Comput 2024. [PMID: 38242854 DOI: 10.1021/acs.jctc.3c01119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2024]
Abstract
Time-dependent electric fields applied to ionic systems can induce both a dielectric and a conductive response, leading to the generation of macroscopic polarization and current, respectively. It has long been recognized that it is not possible to determine the two types of responses separately. However, this aspect is often not adequately accounted for in dielectric and absorption spectroscopies of ionic systems. To clarify this, we theoretically investigate the dielectric and conductive responses of ionic systems containing polyatomic ions based on linear response theory. We derive general expressions for the frequency-dependent dielectric functions, conductivity, and absorption coefficient, including those measured experimentally. Furthermore, we show that the dielectric and conductive responses cannot be uniquely distinguished even at the theoretical level and, therefore, cannot represent experimentally measured quantities. Instead, dielectric and absorption spectra of ionic systems should be expressed in terms of the generalized dielectric function that encompasses both dielectric and conductive responses. We propose a computational method to calculate this generalized dielectric function reliably. Model calculations on concentrated aqueous solutions of NaCl, a monatomic salt, and LiTFSI, a polyatomic salt, show that the dielectric and linear absorption spectra of the two systems based on the generalized dielectric function are significantly different from purely dielectric counterparts in the far-IR, terahertz, and lower-frequency regions. Moreover, the spectra are mainly determined by the autocorrelations of total dipole and total current, but dipole-current cross-correlation can also significantly contribute to the spectra of the LiTFSI solution. The present theoretical approach could be extended to nonlinear spectroscopy of ionic liquids and electrolyte solutions.
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Affiliation(s)
- Jonggu Jeon
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Republic of Korea
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Republic of Korea
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
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6
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Galindo C, Teope RV, Tarabeih L, Ben Ishai P, Feldman Y. Microwave Dielectric Relaxation of Univalent and Bivalent Electrolyte Solutions. J Phys Chem B 2023; 127:10003-10015. [PMID: 37963828 DOI: 10.1021/acs.jpcb.3c05221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
The microwave dielectric relaxation of aqueous solutions of univalent (KCl, NaCl, NaI) and bivalent (CaCl2, MgCl2) electrolytes at concentrations between 0.1 and 1 M at 25 °C was investigated using a vector network analyzer (0.5≤ ν ≤ 40 GHz). The spectra of these electrolyte systems are characterized by a symmetrical broadening of the main relaxation peak and were fitted using the Cole-Cole equation. In our analysis, we provide insights into the underlying physics of the relaxation events at microscopic and mesoscopic scales by using a 3D phase space trajectory that is based on the interactions of the relaxing dipole units with their surroundings and Frohlich's B function. The effect of the solutes on the H-bond network of water with increasing concentration is evident in the microwave dielectric spectra through decreasing dielectric strengths and relaxation times. It was found that the number of perturbed water molecules is higher in the case of bivalent electrolytes and appears to be proportional to the ionic radius. In our approach, the particular dependence between the broadening parameter α and the relaxation times τ reflects the rate of interactions between the elementary dipole units and their surroundings. We provide a quantitative analysis of the level of perturbation caused by the presence of ions in the hydrogen-bond network of water. It was found that the H-bonded network of water is highly perturbed in univalent systems compared to bivalent systems due to weaker bonded hydration shells. Finally, we found significant differences between the dielectric response of NaCl and NaI. The differences, originating in the counterions Cl- and I-, which are characterized by large ionic radii and consequently weaker electric fields in their vicinity, confirm that the effect of weakly hydrated ions should not be neglected in microwave dielectric spectra analysis.
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Affiliation(s)
- Cindy Galindo
- The Hebrew University of Jerusalem, Institute of Applied Physics, Jerusalem 9190401, Israel
| | - Rodolfo Victor Teope
- The Hebrew University of Jerusalem, Institute of Applied Physics, Jerusalem 9190401, Israel
| | - Lama Tarabeih
- The Hebrew University of Jerusalem, Institute of Applied Physics, Jerusalem 9190401, Israel
| | - Paul Ben Ishai
- Department of Physics, Ariel University, Kyriat Hamada St. 3, 40700 Ariel, Israel
| | - Yuri Feldman
- The Hebrew University of Jerusalem, Institute of Applied Physics, Jerusalem 9190401, Israel
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7
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Zhang C, Yue S, Panagiotopoulos AZ, Klein ML, Wu X. Why Dissolving Salt in Water Decreases Its Dielectric Permittivity. PHYSICAL REVIEW LETTERS 2023; 131:076801. [PMID: 37656852 DOI: 10.1103/physrevlett.131.076801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 04/30/2023] [Accepted: 07/07/2023] [Indexed: 09/03/2023]
Abstract
The dielectric permittivity of salt water decreases on dissolving more salt. For nearly a century, this phenomenon has been explained by invoking saturation in the dielectric response of the solvent water molecules. Herein, we employ an advanced deep neural network (DNN), built using data from density functional theory, to study the dielectric permittivity of sodium chloride solutions. Notably, the decrease in the dielectric permittivity as a function of concentration, computed using the DNN approach, agrees well with experiments. Detailed analysis of the computations reveals that the dominant effect, caused by the intrusion of ionic hydration shells into the solvent hydrogen-bond network, is the disruption of dipolar correlations among water molecules. Accordingly, the observed decrease in the dielectric permittivity is mostly due to increasing suppression of the collective response of solvent waters.
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Affiliation(s)
- Chunyi Zhang
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Shuwen Yue
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | | | - Michael L Klein
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
- Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, USA
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Xifan Wu
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
- Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, USA
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8
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Maji D, Biswas R. Dielectric relaxation and dielectric decrement in ionic acetamide deep eutectic solvents: Spectral decomposition and comparison with experiments. J Chem Phys 2023; 158:2888209. [PMID: 37139998 DOI: 10.1063/5.0147378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 04/17/2023] [Indexed: 05/05/2023] Open
Abstract
Frequency-dependent dielectric relaxation in three deep eutectic solvents (DESs), (acetamide+LiClO4/NO3/Br), was investigated in the temperature range, 329 ≤ T/K ≤ 358, via molecular dynamics simulations. Subsequently, decomposition of the real and the imaginary components of the simulated dielectric spectra was carried out to separate the rotational (dipole-dipole), translational (ion-ion), and ro-translational (dipole-ion) contributions. The dipolar contribution, as expected, was found to dominate all the frequency-dependent dielectric spectra over the entire frequency regime, while the other two components together made tiny contributions only. The translational (ion-ion) and the cross ro-translational contributions appeared in the THz regime in contrast to the viscosity-dependent dipolar relaxations that dominated the MHz-GHz frequency window. Our simulations predicted, in agreement with experiments, anion-dependent decrement of the static dielectric constant (ɛs ∼ 20 to 30) for acetamide (ɛs ∼ 66) in these ionic DESs. Simulated dipole-correlations (Kirkwood g factor) indicated significant orientational frustrations. The frustrated orientational structure was found to be associated with the anion-dependent damage of the acetamide H-bond network. Single dipole reorientation time distributions suggested slowed down acetamide rotations but did not indicate presence of any "rotationally frozen" molecule. The dielectric decrement is, therefore, largely static in origin. This provides a new insight into the ion dependence of the dielectric behavior of these ionic DESs. A good agreement between the simulated and the experimental timescales was also noticed.
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Affiliation(s)
- Dhrubajyoti Maji
- Department of Chemical and Biological Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector III, Salt Lake, Kolkata, West Bengal 700106, India
| | - Ranjit Biswas
- Department of Chemical and Biological Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector III, Salt Lake, Kolkata, West Bengal 700106, India
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9
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Woodcox M, Mahata A, Hagerstrom A, Stelson A, Muzny C, Sundararaman R, Schwarz K. Simulating dielectric spectra: A demonstration of the direct electric field method and a new model for the nonlinear dielectric response. J Chem Phys 2023; 158:124122. [PMID: 37003751 DOI: 10.1063/5.0143425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
Abstract
We demonstrate a method to compute the dielectric spectra of fluids in molecular dynamics (MD) by directly applying electric fields to the simulation. We obtain spectra from MD simulations with low magnitude electric fields (≈0.01 V/Å) in agreement with spectra from the fluctuation-dissipation method for water and acetonitrile. We examine this method's trade-off between noise at low field magnitudes and the nonlinearity of the response at higher field magnitudes. We then apply the Booth equation to describe the nonlinear response of both fluids at low frequency (0.1 GHz) and high field magnitude (up to 0.5 V/Å). We develop a model of the frequency-dependent nonlinear response by combining the Booth description of the static nonlinear dielectric response of fluids with the frequency-dependent linear dielectric response of the Debye model. We find good agreement between our model and the MD simulations of the nonlinear dielectric response for both acetonitrile and water.
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Affiliation(s)
- Michael Woodcox
- Theiss Research, P. O. Box 127, La Jolla, California 92038, USA
| | - Avik Mahata
- Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Dr., Gaithersburg, Maryland 20899, USA
| | - Aaron Hagerstrom
- Communications Technology Laboratory, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Angela Stelson
- Communications Technology Laboratory, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Chris Muzny
- Material Measurement Laboratory, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - Ravishankar Sundararaman
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 8th St., Troy, New York 12180, USA
| | - Kathleen Schwarz
- Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Dr., Gaithersburg, Maryland 20899, USA
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10
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Hydration Structures and Dynamics of the Sodium Fluoride Aqueous Solutions at Various Temperatures: Molecular Dynamics Simulations. J SOLUTION CHEM 2022. [DOI: 10.1007/s10953-022-01222-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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11
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Balos V, Kaliannan NK, Elgabarty H, Wolf M, Kühne TD, Sajadi M. Time-resolved terahertz-Raman spectroscopy reveals that cations and anions distinctly modify intermolecular interactions of water. Nat Chem 2022; 14:1031-1037. [PMID: 35773490 PMCID: PMC9417992 DOI: 10.1038/s41557-022-00977-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 05/16/2022] [Indexed: 11/09/2022]
Abstract
The solvation of ions changes the physical, chemical and thermodynamic properties of water, and the microscopic origin of this behaviour is believed to be ion-induced perturbation of water's hydrogen-bonding network. Here we provide microscopic insights into this process by monitoring the dissipation of energy in salt solutions using time-resolved terahertz-Raman spectroscopy. We resonantly drive the low-frequency rotational dynamics of water molecules using intense terahertz pulses and probe the Raman response of their intermolecular translational motions. We find that the intermolecular rotational-to-translational energy transfer is enhanced by highly charged cations and is drastically reduced by highly charged anions, scaling with the ion surface charge density and ion concentration. Our molecular dynamics simulations reveal that the water-water hydrogen-bond strength between the first and second solvation shells of cations increases, while it decreases around anions. The opposite effects of cations and anions on the intermolecular interactions of water resemble the effects of ions on the stabilization and denaturation of proteins.
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Affiliation(s)
- Vasileios Balos
- Fritz Haber Institute of the Max-Planck Society, Berlin, Germany. .,IMDEA Nanociencia, Ciudad Universitaria de Cantoblanco, Madrid, Spain.
| | - Naveen Kumar Kaliannan
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry, University of Paderborn, Paderborn, Germany
| | - Hossam Elgabarty
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry, University of Paderborn, Paderborn, Germany.
| | - Martin Wolf
- Fritz Haber Institute of the Max-Planck Society, Berlin, Germany
| | - Thomas D Kühne
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry, University of Paderborn, Paderborn, Germany
| | - Mohsen Sajadi
- Fritz Haber Institute of the Max-Planck Society, Berlin, Germany. .,Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry, University of Paderborn, Paderborn, Germany.
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12
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Abstract
In this study, we examine the spectral dielectric properties of liquid water in charged nanopores over a wide range of frequencies (0.3 GHz to 30 THz) and pore widths (0.3 to 5 nm). This has been achieved using classical molecular dynamics simulations of hydrated Na-smectite, the prototypical swelling clay mineral. We observe a drastic (20-fold) and anisotropic decrease in the static relative permittivity of the system as the pore width decreases. This large decrement in static permittivity reflects a strong attenuation of the main Debye relaxation mode of liquid water. Remarkably, this strong attenuation entails very little change in the time scale of the collective relaxation. Our results indicate that water confined in charged nanopores is a distinct solvent with a much weaker collective nature than bulk liquid water, in agreement with recent observations of water in uncharged nanopores. Finally, we observe remarkable agreement between the dielectric properties of the simulated clay system against a compiled set of soil samples at various volumetric water contents. This implies that saturation may not be the sole property dictating the dielectric properties of soil samples, rather that the pore-size distribution of fully saturated nanopores may also play a critically important role.
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Affiliation(s)
- Thomas R Underwood
- Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Ian C Bourg
- Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey 08544, United States.,High Meadows Environmental Institute, Princeton University, Princeton, New Jersey 08544, United States
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13
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Ringe S, Hörmann NG, Oberhofer H, Reuter K. Implicit Solvation Methods for Catalysis at Electrified Interfaces. Chem Rev 2021; 122:10777-10820. [PMID: 34928131 PMCID: PMC9227731 DOI: 10.1021/acs.chemrev.1c00675] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
![]()
Implicit solvation
is an effective, highly coarse-grained approach
in atomic-scale simulations to account for a surrounding liquid electrolyte
on the level of a continuous polarizable medium. Originating in molecular
chemistry with finite solutes, implicit solvation techniques are now
increasingly used in the context of first-principles modeling of electrochemistry
and electrocatalysis at extended (often metallic) electrodes. The
prevalent ansatz to model the latter electrodes and the reactive surface
chemistry at them through slabs in periodic boundary condition supercells
brings its specific challenges. Foremost this concerns the difficulty
of describing the entire double layer forming at the electrified solid–liquid
interface (SLI) within supercell sizes tractable by commonly employed
density functional theory (DFT). We review liquid solvation methodology
from this specific application angle, highlighting in particular its
use in the widespread ab initio thermodynamics approach
to surface catalysis. Notably, implicit solvation can be employed
to mimic a polarization of the electrode’s electronic density
under the applied potential and the concomitant capacitive charging
of the entire double layer beyond the limitations of the employed
DFT supercell. Most critical for continuing advances of this effective
methodology for the SLI context is the lack of pertinent (experimental
or high-level theoretical) reference data needed for parametrization.
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Affiliation(s)
- Stefan Ringe
- Department of Energy Science and Engineering, Daegu Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea.,Energy Science & Engineering Research Center, Daegu Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - Nicolas G Hörmann
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany.,Chair for Theoretical Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraße 4, D-85747 Garching, Germany
| | - Harald Oberhofer
- Chair for Theoretical Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraße 4, D-85747 Garching, Germany.,Chair for Theoretical Physics VII and Bavarian Center for Battery Technology (BayBatt), University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany
| | - Karsten Reuter
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
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14
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Saravi SH, Panagiotopoulos AZ. Activity coefficients of aqueous electrolytes from implicit-water molecular dynamics simulations. J Chem Phys 2021; 155:184501. [PMID: 34773944 DOI: 10.1063/5.0064963] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We obtain activity coefficients in NaCl and KCl solutions from implicit-water molecular dynamics simulations, at 298.15 K and 1 bar, using two distinct approaches. In the first approach, we consider ions in a continuum with constant relative permittivity (ɛr) equal to that of pure water; in the other approach, we take into account the concentration-dependence of ɛr, as obtained from explicit-water simulations. Individual ion activity coefficients (IIACs) are calculated using gradual insertion of single ions with uniform neutralizing backgrounds to ensure electroneutrality. Mean ionic activity coefficients (MIACs) obtained from the corresponding IIACs in simulations with constant ɛr show reasonable agreement with experimental data for both salts. Surprisingly, large systematic negative deviations are observed for both IIACs and MIACs in simulations with concentration-dependent ɛr. Our results suggest that the absence of hydration structure in implicit-water simulations cannot be compensated by correcting for the concentration-dependence of the relative permittivity ɛr. Moreover, even in simulations with constant ɛr for which the calculated MIACs are reasonable, the relative positioning of IIACs of anions and cations is incorrect for NaCl. We conclude that there are severe inherent limitations associated with implicit-water simulations in providing accurate activities of aqueous electrolytes, a finding with direct relevance to the development of electrolyte theories and to the use and interpretation of implicit-solvent simulations.
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Affiliation(s)
- Sina Hassanjani Saravi
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
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15
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Loche P, Steinbrunner P, Friedowitz S, Netz RR, Bonthuis DJ. Transferable Ion Force Fields in Water from a Simultaneous Optimization of Ion Solvation and Ion-Ion Interaction. J Phys Chem B 2021; 125:8581-8587. [PMID: 34292738 PMCID: PMC8389903 DOI: 10.1021/acs.jpcb.1c05303] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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The poor performance
of many existing nonpolarizable ion force
fields is typically blamed on either the lack of explicit polarizability,
the absence of charge transfer, or the use of unreduced Coulomb interactions.
However, this analysis disregards the large and mostly unexplored
parameter range offered by the Lennard-Jones potential. We use a global
optimization procedure to develop water-model-transferable force fields
for the ions K+, Na+, Cl–,
and Br– in the complete parameter space of all Lennard-Jones
interactions using standard mixing rules. No extra-thermodynamic assumption
is necessary for the simultaneous optimization of the four ion pairs.
After an optimization with respect to the experimental solvation free
energy and activity, the force fields reproduce the concentration-dependent
density, ionic conductivity, and dielectric constant with high accuracy.
The force field is fully transferable between simple point charge/extended
and transferable intermolecular potential water models. Our results
show that a thermodynamically consistent force field for these ions
needs only Lennard-Jones and standard Coulomb interactions.
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Affiliation(s)
- Philip Loche
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | | | - Sean Friedowitz
- Department of Materials Science and Engineering, Stanford University, Stanford 94305, California, United States
| | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Douwe Jan Bonthuis
- Institute of Theoretical and Computational Physics, Graz University of Technology, 8010 Graz, Austria
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16
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Rezaei M, Mitterwallner BG, Loche P, Uematsu Y, Netz RR, Bonthuis DJ. Interfacial, Electroviscous, and Nonlinear Dielectric Effects on Electrokinetics at Highly Charged Surfaces. J Phys Chem B 2021; 125:4767-4778. [PMID: 33939436 PMCID: PMC8154604 DOI: 10.1021/acs.jpcb.0c11280] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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The dielectric constant
and the viscosity of water at the interface
of hydrophilic surfaces differ from their bulk values, and it has
been proposed that the deviation is caused by the strong electric
field and the high ion concentration in the interfacial layer. We
calculate the dependence of the dielectric constant and the viscosity
of bulk electrolytes on the electric field and the salt concentration.
Incorporating the concentration and field-dependent dielectric constant
and viscosity in the extended Poisson–Boltzmann and Stokes
equations, we calculate the electro-osmotic mobility. We compare the
results to literature experimental data and explicit molecular dynamics
simulations of OH-terminated surfaces and show that it is necessary
to additionally include the presence of a subnanometer wide interfacial
water layer, the properties of which are drastically transformed by
the sheer presence of the interface. We conclude that the origin of
the anomalous behavior of aqueous interfacial layers cannot be found
in electrostriction or electroviscous effects caused by the interfacial
electric field and ion concentration. Instead, it is primarily caused
by the intrinsic ordering and orientation of the interfacial water
layer.
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Affiliation(s)
- Majid Rezaei
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | | | - Philip Loche
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Yuki Uematsu
- Department of Physics, Kyushu University, 819-0395 Fukuoka, Japan
| | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Douwe Jan Bonthuis
- Institute of Theoretical and Computational Physics, Graz University of Technology, 8010 Graz, Austria
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17
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Patel LA, Yoon TJ, Currier RP, Maerzke KA. NaCl aggregation in water at elevated temperatures and pressures: Comparison of classical force fields. J Chem Phys 2021; 154:064503. [PMID: 33588550 DOI: 10.1063/5.0030962] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The properties of water vary dramatically with temperature and density. This can be exploited to control its effectiveness as a solvent. Thus, supercritical water is of keen interest as solvent in many extraction processes. The low solubility of salts in lower density supercritical water has even been suggested as a means of desalination. The high temperatures and pressures required to reach supercritical conditions can present experimental challenges during collection of required physical property and phase equilibria data, especially in salt-containing systems. Molecular simulations have the potential to be a valuable tool for examining the behavior of solvated ions at these high temperatures and pressures. However, the accuracy of classical force fields under these conditions is unclear. We have, therefore, undertaken a parametric study of NaCl in water, comparing several salt and water models at 200 bar-600 bar and 450 K-750 K for a range of salt concentrations. We report a comparison of structural properties including ion aggregation, hydrogen bonding, density, and static dielectric constants. All of the force fields qualitatively reproduce the trends in the liquid phase density. An increase in ion aggregation with decreasing density holds true for all of the force fields. The propensity to aggregate is primarily determined by the salt force field rather than the water force field. This coincides with a decrease in the water static dielectric constant and reduced charge screening. While a decrease in the static dielectric constant with increasing NaCl concentration is consistent across all model combinations, the salt force fields that exhibit more ionic aggregation yield a slightly smaller dielectric decrement.
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Affiliation(s)
- Lara A Patel
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Tae Jun Yoon
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Robert P Currier
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Katie A Maerzke
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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18
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Macroscopic conductivity of aqueous electrolyte solutions scales with ultrafast microscopic ion motions. Nat Commun 2020; 11:1611. [PMID: 32235854 PMCID: PMC7109088 DOI: 10.1038/s41467-020-15450-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 03/12/2020] [Indexed: 01/13/2023] Open
Abstract
Despite the widespread use of aqueous electrolytes as conductors, the molecular mechanism of ionic conductivity at moderate to high electrolyte concentrations remains largely unresolved. Using a combination of dielectric spectroscopy and molecular dynamics simulations, we show that the absorption of electrolytes at ~0.3 THz sensitively reports on the local environment of ions. The magnitude of these high-frequency ionic motions scales linearly with conductivity for a wide range of ions and concentrations. This scaling is rationalized within a harmonic oscillator model based on the potential of mean force extracted from simulations. Our results thus suggest that long-ranged ionic transport is intimately related to the local energy landscape and to the friction for short-ranged ion dynamics: a high macroscopic electrolyte conductivity is thereby shown to be related to large-amplitude motions at a molecular scale.
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19
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Honorio T, Bore T, Benboudjema F, Vourc’h E, Ferhat M. Dielectric properties of the pore solution in cement-based materials. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.112548] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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20
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Coles SW, Park C, Nikam R, Kanduč M, Dzubiella J, Rotenberg B. Correlation Length in Concentrated Electrolytes: Insights from All-Atom Molecular Dynamics Simulations. J Phys Chem B 2020; 124:1778-1786. [PMID: 32031810 DOI: 10.1021/acs.jpcb.9b10542] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We study the correlation length of the charge-charge pair correlations in concentrated electrolyte solutions by means of all-atom, explicit-solvent molecular dynamics simulations. We investigate LiCl and NaI in water, which constitute highly soluble, prototypical salts for experiments, as well as two more complex, molecular electrolyte systems of lithium bis(trifluoromethane)sulfonimide (LiTFSI), a salt commonly employed in electrochemical storage systems, in water, and in an organic solvent mixture of dimethoxyethane and dioxolane. Our simulations support the recent experimental observations as well as theoretical predictions of a nonmonotonic behavior of the correlation length with increasing salt concentration. We observe a Debye-Hückel like regime at low concentration, followed by a minimum reached when d/λD ≃ 1, where λD is the Debye correlation length and d is the effective ionic diameter, and an increasing correlation length with salt concentration in very concentrated electrolytes. As in the experiments, we find that the screening length in the concentrated regime follows a universal scaling law as a function d/λD for all studied salts. However, the scaling exponent is significantly lower than the experimentally measured one and lies in the range of the theoretical predictions based on much simpler electrolyte models.
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Affiliation(s)
- Samuel W Coles
- Sorbonne Université, CNRS, Physicochimie des électrolytes et Nanosystèmes Interfaciaux, UMR PHENIX, 4 pl. Jussieu, F-75005 Paris, France
| | - Chanbum Park
- Research Group for Simulations of Energy Materials, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany.,Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, D-12489 Berlin, Germany
| | - Rohit Nikam
- Research Group for Simulations of Energy Materials, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany.,Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, D-12489 Berlin, Germany
| | - Matej Kanduč
- Research Group for Simulations of Energy Materials, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany.,Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Joachim Dzubiella
- Research Group for Simulations of Energy Materials, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany.,Applied Theoretical Physics-Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg, Germany
| | - Benjamin Rotenberg
- Sorbonne Université, CNRS, Physicochimie des électrolytes et Nanosystèmes Interfaciaux, UMR PHENIX, F-75005 Paris, France
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21
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Seal S, Doblhoff-Dier K, Meyer J. Dielectric Decrement for Aqueous NaCl Solutions: Effect of Ionic Charge Scaling in Nonpolarizable Water Force Fields. J Phys Chem B 2019; 123:9912-9921. [PMID: 31647235 PMCID: PMC6875873 DOI: 10.1021/acs.jpcb.9b07916] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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We investigate the dielectric constant and the dielectric decrement of aqueous NaCl
solutions by means of molecular dynamic simulations. We thereby compare the performance
of four different force fields and focus on disentangling the origin of the dielectric
decrement and the influence of scaled ionic charges, as often used in nonpolarizable
force fields to account for the missing dynamic polarizability in the shielding of
electrostatic ion interactions. Three of the force fields showed excessive contact ion
pair formation, which correlates with a reduced dielectric decrement. In spite of the
fact that the scaling of charges only weakly influenced the average polarization of
water molecules around an ion, the rescaling of ionic charges did influence the
dielectric decrement, and a close-to-linear relation of the slope of the dielectric
constant as a function of concentration with the ionic charge was found.
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Affiliation(s)
- Sayan Seal
- Gorlaeus Laboratories, Leiden Institute of Chemistry , Leiden University , PO Box 9502, 2300 RA Leiden , The Netherlands
| | - Katharina Doblhoff-Dier
- Gorlaeus Laboratories, Leiden Institute of Chemistry , Leiden University , PO Box 9502, 2300 RA Leiden , The Netherlands
| | - Jörg Meyer
- Gorlaeus Laboratories, Leiden Institute of Chemistry , Leiden University , PO Box 9502, 2300 RA Leiden , The Netherlands
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22
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Affiliation(s)
- Stephen J. Cox
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Michiel Sprik
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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23
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Schlaich A, Dos Santos AP, Netz RR. Simulations of Nanoseparated Charged Surfaces Reveal Charge-Induced Water Reorientation and Nonadditivity of Hydration and Mean-Field Electrostatic Repulsion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:551-560. [PMID: 30571136 DOI: 10.1021/acs.langmuir.8b03474] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We perform atomistic simulations of nanometer-separated charged surfaces in the presence of monovalent counterions at fixed water chemical potential. The counterion density profiles are well described by a modified Poisson-Boltzmann (MPB) approach that accounts for nonelectrostatic ion-surface interactions, while the effects of smeared-out surface-charge distributions and dielectric profiles are found to be relatively unimportant. The simulated surface interactions are for weakly charged surfaces well described by the additive contributions of hydration and MPB repulsions, but already for a moderate surface charge density of σ = -0.77 e/nm2 this additivity breaks down. This we rationalize by a combination of different effects, namely, counterion correlations as well as the surface charge-induced reorientation of hydration water, which modifies the effective water dielectric constant as well as the hydration repulsion.
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Affiliation(s)
- Alexander Schlaich
- Laboratoire Interdisciplinaire de Physique, CNRS and Université Grenoble Alpes, UMR CNRS 5588, 38000 Grenoble , France
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Alexandre P Dos Santos
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
- Instituto de Física , Universidade Federal do Rio Grande do Sul , CEP 91501-970, 15051 Porto Alegre , Brazil
| | - Roland R Netz
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
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24
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Schwaab G, Sebastiani F, Havenith M. Untersuchung von Ionenhydratation und Ionenpaarbildung mittels THz‐Spektroskopie. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201805261] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Gerhard Schwaab
- Lehrstuhl für Physikalische Chemie IIRuhr-Universität Bochum 44780 Bochum Deutschland
| | - Federico Sebastiani
- Lehrstuhl für Physikalische Chemie IIRuhr-Universität Bochum 44780 Bochum Deutschland
| | - Martina Havenith
- Lehrstuhl für Physikalische Chemie IIRuhr-Universität Bochum 44780 Bochum Deutschland
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25
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Schwaab G, Sebastiani F, Havenith M. Ion Hydration and Ion Pairing as Probed by THz Spectroscopy. Angew Chem Int Ed Engl 2018; 58:3000-3013. [PMID: 30022575 DOI: 10.1002/anie.201805261] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 07/17/2018] [Indexed: 11/12/2022]
Abstract
Ion hydration is of pivotal importance for many fundamental processes. Various spectroscopic methods are used to study the retardation of the hydration bond dynamics in the vicinity of anions and cations. Here we introduce THz-FTIR spectroscopy as a powerful method to answer the open questions. We show through dissection of THz spectra that we can pinpoint characteristic absorption features that can be attributed to the rattling modes of strongly hydrating ions within their hydration cages as well as vibrationally induced charge fluctuations in the case of weakly hydrating ions. Further analysis yields information on anion-cation cooperativity, the size of the dynamic hydration shell, as well as the lifetimes of these collective ion-hydration water modes and their connecting thermal bath states. Our study provides evidence for a non-additive behavior, thus questioning the simplified Hofmeister model. THz spectroscopy enables ion pairing to be observed and quantified at a high salt concentration.
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Affiliation(s)
- Gerhard Schwaab
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Federico Sebastiani
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Martina Havenith
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany
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26
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Uematsu Y, Netz RR, Bonthuis DJ. Analytical Interfacial Layer Model for the Capacitance and Electrokinetics of Charged Aqueous Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9097-9113. [PMID: 29495657 DOI: 10.1021/acs.langmuir.7b04171] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We construct an analytical model to account for the influence of the subnanometer-wide interfacial layer on the differential capacitance and the electro-osmotic mobility of solid-electrolyte interfaces. The interfacial layer is incorporated into the Poisson-Boltzmann and Stokes equations using a box model for the dielectric properties, the viscosity, and the ionic potential of mean force. We calculate the differential capacitance and the electro-osmotic mobility as a function of the surface charge density and the salt concentration, both with and without steric interactions between the ions. We compare the results from our theoretical model with experimental data on a variety of systems (graphite and metallic silver for capacitance and titanium oxide and silver iodide for electro-osmotic data). The differential capacitance of silver as a function of salinity and surface charge density is well reproduced by our theory, using either the width of the interfacial layer or the ionic potential of mean force as the only fitting parameter. The differential capacitance of graphite, however, needs an additional carbon capacitance to explain the experimental data. Our theory yields a power-law dependence of the electro-osmotic mobility on the surface charge density for high surface charges, reproducing the experimental data using both the interfacial parameters extracted from molecular dynamics simulations and fitted interfacial parameters. Finally, we examine different types of hydrodynamic boundary conditions for the power-law behavior of the electro-osmotic mobility, showing that a finite-viscosity layer explains the experimental data better than the usual hydrodynamic slip boundary condition. Our analytical model thus allows us to extract the properties of the subnanometer-wide interfacial layer by fitting to macroscopic experimental data.
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Affiliation(s)
- Yuki Uematsu
- Department of Chemistry , Kyushu University , Fukuoka 819-0395 , Japan
- Fachbereich Physik , Freie Universität Berlin , 14195 Berlin , Germany
| | - Roland R Netz
- Fachbereich Physik , Freie Universität Berlin , 14195 Berlin , Germany
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27
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Mamatkulov SI, Rinne KF, Buchner R, Netz RR, Bonthuis DJ. Water-separated ion pairs cause the slow dielectric mode of magnesium sulfate solutions. J Chem Phys 2018; 148:222812. [DOI: 10.1063/1.5000385] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Shavkat I. Mamatkulov
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
- Ion-Plasma and Laser Technologies Institute of the Uzbekistan AS, Tashkent, Uzbekistan
| | - Klaus F. Rinne
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Richard Buchner
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, D-93040 Regensburg, Germany
| | - Roland R. Netz
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
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28
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Zhang Q, Pan Z, Zhang L, Zhang R, Chen Z, Jin T, Wu T, Chen X, Zhuang W. Ion effect on the dynamics of water hydrogen bonding network: A theoretical and computational spectroscopy point of view. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2018. [DOI: 10.1002/wcms.1373] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Qiang Zhang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouChina
- Department of ChemistryBohai UniversityJinzhouChina
| | - Zhijun Pan
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouChina
| | - Lu Zhang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouChina
| | - Ruiting Zhang
- School of Physics and Optoelectronic EngineeringXidian UniversityXi'anChina
| | - Zhening Chen
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouChina
| | - Tan Jin
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouChina
| | - Tianmin Wu
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouChina
| | - Xian Chen
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouChina
| | - Wei Zhuang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouChina
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29
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Pache D, Schmid R. Molecular Dynamics Investigation of the Dielectric Decrement of Ion Solutions. ChemElectroChem 2018. [DOI: 10.1002/celc.201800158] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Dennis Pache
- Computational Materials Chemistry Research Group, Department of Inorganic Chemistry II; Ruhr University Bochum; Germany
| | - Rochus Schmid
- Computational Materials Chemistry Research Group, Department of Inorganic Chemistry II; Ruhr University Bochum; Germany
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30
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Interpretation of the GHz to THz dielectric relaxation dynamics of water in the framework of the Coupling Model. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.01.039] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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Uematsu Y, Netz RR, Bonthuis DJ. The effects of ion adsorption on the potential of zero charge and the differential capacitance of charged aqueous interfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:064002. [PMID: 29297853 DOI: 10.1088/1361-648x/aaa4d4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Using a box profile approximation for the non-electrostatic surface adsorption potentials of anions and cations, we calculate the differential capacitance of aqueous electrolyte interfaces from a numerical solution of the Poisson-Boltzmann equation, including steric interactions between the ions and an inhomogeneous dielectric profile. Preferential adsorption of the positive (negative) ion shifts the minimum of the differential capacitance to positive (negative) surface potential values. The trends are similar for the potential of zero charge; however, the potential of zero charge does not correspond to the minimum of the differential capacitance in the case of asymmetric ion adsorption, contrary to the assumption commonly used to determine the potential of zero charge. Our model can be used to obtain more accurate estimates of ion adsorption properties from differential capacitance or electrocapillary measurements. Asymmetric ion adsorption also affects the relative heights of the characteristic maxima in the differential capacitance curves as a function of the surface potential, but even for strong adsorption potentials the effect is small, making it difficult to reliably determine the adsorption properties from the peak heights.
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Affiliation(s)
- Yuki Uematsu
- Department of Chemistry, Kyushu University, Fukuoka 819-0395, Japan. Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
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32
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Schaaf C, Gekle S. Spatially resolved dielectric constant of confined water and its connection to the non-local nature of bulk water. J Chem Phys 2016; 145:084901. [DOI: 10.1063/1.4960775] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Christian Schaaf
- Institute of Theoretical Physics, Technical University Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
- Biofluid Simulation and Modeling, Fachbereich Physik, Universität Bayreuth, Universitätsstraße 30, Bayreuth 95440, Germany
| | - Stephan Gekle
- Biofluid Simulation and Modeling, Fachbereich Physik, Universität Bayreuth, Universitätsstraße 30, Bayreuth 95440, Germany
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33
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Liu S, Jia GZ. The dielectric properties of LiOH aqueous solution under external electromagnetic fields by molecular dynamics simulation. J Mol Liq 2016. [DOI: 10.1016/j.molliq.2016.01.090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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34
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Rinne KF, Schulz JCF, Netz RR. Impact of secondary structure and hydration water on the dielectric spectrum of poly-alanine and possible relation to the debate on slaved versus slaving water. J Chem Phys 2016; 142:215104. [PMID: 26049528 DOI: 10.1063/1.4921777] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using extensive molecular dynamics simulations of a single eight-residue alanine polypeptide in explicit water, we investigate the influence of α-helix formation on the dielectric spectrum. For this, we project long equilibrium trajectories into folded and unfolded states and thereby obtain dielectric spectra representative for disordered as well α-helical conformations without the need to change any other system parameter such as pH or temperature. The absorption spectrum in the α-helical state exhibits a feature in the sub-GHz range that is significantly stronger than in the unfolded state. As we show by an additional decomposition into peptide and water contributions, this slow dielectric mode, the relaxation time of which matches the independently determined peptide rotational relaxation time, is mostly caused by peptide polarization correlations, but also contains considerable contributions from peptide-water correlations. In contrast, the peptide spectral contribution shows no features in the GHz range where bulk water absorbs, not even in the peptide-water correlation part, we conclude that hydration water around Ala8 is more influenced by peptide polarization relaxation effects than the other way around. A further decomposition into water-self and water-collective polarization correlations shows that the dielectric response of hydration water is, in contrast to electrolyte solutions, retarded and that this retardation is mostly due to collective effects, the self relaxation of hydration water molecules is only slightly slowed down compared to bulk water. We find the dynamic peptide-water polarization cross correlations to be rather long-ranged and to extend more than one nanometer away from the peptide-water interface into the water hydration shell, in qualitative agreement with previous simulation studies and recent THz absorption experiments.
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Affiliation(s)
- Klaus F Rinne
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | | | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
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Kim WK, Netz RR. Barrier-induced dielectric counterion relaxation at super-low frequencies in salt-free polyelectrolyte solutions. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2015; 38:120. [PMID: 26590150 DOI: 10.1140/epje/i2015-15120-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 10/20/2015] [Indexed: 06/05/2023]
Abstract
Based on the thermally activated diffusion of counterions over the barrier of the electrostatic binding potential, we construct a scaling theory for the slow dielectric response in dilute and semi-dilute polyelectrolyte solutions. The theory is based on an analytic evaluation of the mean-escape time of a single counterion from the surface of a polyelectrolyte chain and uses a variational expression for the electrostatic potential of a charged cylinder including counterion condensation. This mean-escape time shows a range of characteristic power-law dependencies on the polyelectrolyte length and the polyelectrolyte monomer concentration. The existence of this novel dielectric mode at super-low frequencies reflects the wide spectrum of experimental findings for the super-low-frequency dielectric relaxation mode and thereby helps to reconcile conflicting interpretations of experimental data in terms of conventional scaling laws. We also devise a scaling theory for the counterion condensation of finite-length polyelectrolyte chains at finite concentration, which allows us to include polyelectrolyte charge renormalization in dilute as well as semi-dilute solutions in a unified theoretical framework.
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Affiliation(s)
- Won Kyu Kim
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
| | - Roland R Netz
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
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Jahn M, Gekle S. Bulk and interfacial liquid water as a transient network. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:052130. [PMID: 26651669 DOI: 10.1103/physreve.92.052130] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Indexed: 06/05/2023]
Abstract
The special macroscopic properties of liquid water stem from its structure as a complex network of molecules connected by hydrogen bonds. While the dynamics of single molecules within this network has been extensively investigated, only little attention has been paid to the closed loops (meshes) of hydrogen-bonded molecules which determine the network topology. Using molecular dynamics simulations we analyze the size, shape, geometrical arrangement, and dynamical stability of loops containing up to 10 hydrogen bonds. We find that six-membered loops in liquid water even at room temperature retain a striking similarity with the well-known structure of ice. Analyzing the network dynamics we find that rings of more than five hydrogen bonds are stabilized compared to a random collection containing the same number of single bonds. We finally show that in the vicinity of hydrophobic and hydrophilic interfaces loops arrange in a preferred orientation.
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Affiliation(s)
- Miriam Jahn
- Fachbereich Physik, Universität Bayreuth, Germany
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Schaaf C, Gekle S. Dielectric response of the water hydration layer around spherical solutes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:032718. [PMID: 26465509 DOI: 10.1103/physreve.92.032718] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Indexed: 06/05/2023]
Abstract
We calculate the local dielectric function ɛ(r) inside the hydration layer around a spherical solute (i) from molecular dynamics simulations including explicit solutes and (ii) theoretically using the nonlocal dielectric function of bulk water which includes the radial electric field, but not the explicit solute. The observed agreement between the two concepts shows that while ɛ(r) is strongly different from bulk, this difference is not due to restructuring of the hydrogen bond network but is mostly a consequence of the field geometry. The dielectric response differs for anions and cations, yielding a natural explanation for the well-known charge asymmetry of ionic solvation in agreement with experimental data.
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Affiliation(s)
- Christian Schaaf
- Biofluid Simulation and Modeling, Department of Physics, University of Bayreuth, 95440 Bayreuth, Germany
| | - Stephan Gekle
- Biofluid Simulation and Modeling, Department of Physics, University of Bayreuth, 95440 Bayreuth, Germany
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Duan X, Nakamura I. A new lattice Monte Carlo simulation for dielectric saturation in ion-containing liquids. SOFT MATTER 2015; 11:3566-3571. [PMID: 25807274 DOI: 10.1039/c5sm00336a] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We develop a new, rapid method for the lattice Monte Carlo simulation of ion-containing liquids that accounts for the effects of the reorganization of solvent dipoles under external electrostatic fields. Our results are in reasonable agreement with the analytical solutions to the dielectric continuum theory of Booth for single ions, ion pairs, and ionic cross-links. We also illustrate the substantial disparity between the dielectric functions for like and unlike charges on the nanometer scale. Our simulation rationalizes the experimental data for the dependence of the bulk dielectric value of water on ion concentrations in terms of saturated dipoles near ions.
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Affiliation(s)
- Xiaozheng Duan
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China.
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