1
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Moon S, Limmer DT. Enhanced ClNO 2 Formation at the Interface of Sea-Salt Aerosol. J Phys Chem Lett 2024:9466-9473. [PMID: 39254177 DOI: 10.1021/acs.jpclett.4c02289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Abstract
The reactive uptake of N2O5 on sea-spray aerosol plays a key role in regulating the NOx concentration in the troposphere. Despite numerous field and laboratory studies, a microscopic understanding of its heterogeneous reactivity remains unclear. Here, we use molecular simulation and theory to elucidate the chlorination of N2O5 to form ClNO2, the primary reactive channel within sea-spray aerosol. We find that the formation of ClNO2 is markedly enhanced at the air-water interface due to the stabilization of the charge-delocalized transition state, as evident from the formulation of bimolecular rate theory in heterogeneous environments. We explore the consequences of the enhanced interfacial reactivity in the uptake of N2O5 using numerical solutions of molecular reaction-diffusion equations as well as their analytical approximations. Our results suggest that the current interpretation of aerosol branching ratios needs to be revisited.
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Affiliation(s)
- Seokjin Moon
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - David T Limmer
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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2
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France-Lanord A, Vroylandt H, Salanne M, Rotenberg B, Saitta AM, Pietrucci F. Data-Driven Path Collective Variables. J Chem Theory Comput 2024; 20:3069-3084. [PMID: 38619076 DOI: 10.1021/acs.jctc.4c00123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Identifying optimal collective variables to model transformations using atomic-scale simulations is a long-standing challenge. We propose a new method for the generation, optimization, and comparison of collective variables that can be thought of as a data-driven generalization of the path collective variable concept. It consists of a kernel ridge regression of the committor probability, which encodes a transformation's progress. The resulting collective variable is one-dimensional, interpretable, and differentiable, making it appropriate for enhanced sampling simulations requiring biasing. We demonstrate the validity of the method on two different applications: a precipitation model and the association of Li+ and F- in water. For the former, we show that global descriptors such as the permutation invariant vector allow reaching an accuracy far from the one achieved via simpler, more intuitive variables. For the latter, we show that information correlated with the transformation mechanism is contained in the first solvation shell only and that inertial effects prevent the derivation of optimal collective variables from the atomic positions only.
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Affiliation(s)
- Arthur France-Lanord
- Institut des Sciences du Calcul et des Données, ISCD, Sorbonne Université, F-75005 Paris, France
- Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, Sorbonne Université, F-75005 Paris, France
| | - Hadrien Vroylandt
- Institut des Sciences du Calcul et des Données, ISCD, Sorbonne Université, F-75005 Paris, France
| | - Mathieu Salanne
- Physicochimie des Électrolytes et Nanosystèmes Interfaciaux, Sorbonne Université, CNRS, 4 Place Jussieu, F-75005 Paris, France
- Institut Universitaire de France (IUF), 75231 Paris, France
| | - Benjamin Rotenberg
- Physicochimie des Électrolytes et Nanosystèmes Interfaciaux, Sorbonne Université, CNRS, 4 Place Jussieu, F-75005 Paris, France
| | - A Marco Saitta
- Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, Sorbonne Université, F-75005 Paris, France
| | - Fabio Pietrucci
- Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, Sorbonne Université, F-75005 Paris, France
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3
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Herringer NSM, Dasetty S, Gandhi D, Lee J, Ferguson AL. Permutationally Invariant Networks for Enhanced Sampling (PINES): Discovery of Multimolecular and Solvent-Inclusive Collective Variables. J Chem Theory Comput 2024; 20:178-198. [PMID: 38150421 DOI: 10.1021/acs.jctc.3c00923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
The typically rugged nature of molecular free-energy landscapes can frustrate efficient sampling of the thermodynamically relevant phase space due to the presence of high free-energy barriers. Enhanced sampling techniques can improve phase space exploration by accelerating sampling along particular collective variables (CVs). A number of techniques exist for the data-driven discovery of CVs parametrizing the important large-scale motions of the system. A challenge to CV discovery is learning CVs invariant to the symmetries of the molecular system, frequently rigid translation, rigid rotation, and permutational relabeling of identical particles. Of these, permutational invariance has proved a persistent challenge in frustrating the data-driven discovery of multimolecular CVs in systems of self-assembling particles and solvent-inclusive CVs for solvated systems. In this work, we integrate permutation invariant vector (PIV) featurizations with autoencoding neural networks to learn nonlinear CVs invariant to translation, rotation, and permutation and perform interleaved rounds of CV discovery and enhanced sampling to iteratively expand the sampling of configurational phase space and obtain converged CVs and free-energy landscapes. We demonstrate the permutationally invariant network for enhanced sampling (PINES) approach in applications to the self-assembly of a 13-atom argon cluster, association/dissociation of a NaCl ion pair in water, and hydrophobic collapse of a C45H92 n-pentatetracontane polymer chain. We make the approach freely available as a new module within the PLUMED2 enhanced sampling libraries.
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Affiliation(s)
| | - Siva Dasetty
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Diya Gandhi
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Junhee Lee
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Andrew L Ferguson
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
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4
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Hoang Ngoc Minh T, Kim J, Pireddu G, Chubak I, Nair S, Rotenberg B. Electrical noise in electrolytes: a theoretical perspective. Faraday Discuss 2023; 246:198-224. [PMID: 37409620 DOI: 10.1039/d3fd00026e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Seemingly unrelated experiments such as electrolyte transport through nanotubes, nano-scale electrochemistry, NMR relaxometry and surface force balance measurements, all probe electrical fluctuations: of the electric current, the charge and polarization, the field gradient (for quadrupolar nuclei) and the coupled mass/charge densities. The fluctuations of such various observables arise from the same underlying microscopic dynamics of the ions and solvent molecules. In principle, the relevant length and time scales of these dynamics are encoded in the dynamic structure factors. However, modelling the latter for frequencies and wavevectors spanning many orders of magnitude remains a great challenge to interpret the experiments in terms of physical processes such as solvation dynamics, diffusion, electrostatic and hydrodynamic interactions between ions, interactions with solid surfaces, etc. Here, we highlight the central role of the charge-charge dynamic structure factor in the fluctuations of electrical observables in electrolytes and offer a unifying perspective over a variety of complementary experiments. We further analyze this quantity in the special case of an aqueous NaCl electrolyte, using simulations with explicit ions and an explicit or implicit solvent. We discuss the ability of the standard Poisson-Nernst-Planck theory to capture the simulation results, and how the predictions can be improved. We finally discuss the contributions of ions and water to the total charge fluctuations. This work illustrates an ongoing effort towards a comprehensive understanding of electrical fluctuations in bulk and confined electrolytes, in order to enable experimentalists to decipher the microscopic properties encoded in the measured electrical noise.
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Affiliation(s)
- Thê Hoang Ngoc Minh
- Sorbonne Université, CNRS, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France.
| | - Jeongmin Kim
- Sorbonne Université, CNRS, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France.
| | - Giovanni Pireddu
- Sorbonne Université, CNRS, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France.
| | - Iurii Chubak
- Sorbonne Université, CNRS, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France.
| | - Swetha Nair
- Sorbonne Université, CNRS, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France.
| | - Benjamin Rotenberg
- Sorbonne Université, CNRS, Physicochimie des Électrolytes et Nanosystèmes Interfaciaux, F-75005 Paris, France.
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, 80039 Amiens Cedex, France
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5
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Water-Mediated attraction between Like-charged species involved in calcium phosphate nucleation. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
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6
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Jung H, Covino R, Arjun A, Leitold C, Dellago C, Bolhuis PG, Hummer G. Machine-guided path sampling to discover mechanisms of molecular self-organization. NATURE COMPUTATIONAL SCIENCE 2023; 3:334-345. [PMID: 38177937 PMCID: PMC10766509 DOI: 10.1038/s43588-023-00428-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 03/10/2023] [Indexed: 01/06/2024]
Abstract
Molecular self-organization driven by concerted many-body interactions produces the ordered structures that define both inanimate and living matter. Here we present an autonomous path sampling algorithm that integrates deep learning and transition path theory to discover the mechanism of molecular self-organization phenomena. The algorithm uses the outcome of newly initiated trajectories to construct, validate and-if needed-update quantitative mechanistic models. Closing the learning cycle, the models guide the sampling to enhance the sampling of rare assembly events. Symbolic regression condenses the learned mechanism into a human-interpretable form in terms of relevant physical observables. Applied to ion association in solution, gas-hydrate crystal formation, polymer folding and membrane-protein assembly, we capture the many-body solvent motions governing the assembly process, identify the variables of classical nucleation theory, uncover the folding mechanism at different levels of resolution and reveal competing assembly pathways. The mechanistic descriptions are transferable across thermodynamic states and chemical space.
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Affiliation(s)
- Hendrik Jung
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Roberto Covino
- Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany
| | - A Arjun
- van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | | | | | - Peter G Bolhuis
- van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
- Institute of Biophysics, Goethe University Frankfurt, Frankfurt am Main, Germany.
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7
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Gao A, Remsing RC, Weeks JD. Local Molecular Field Theory for Coulomb Interactions in Aqueous Solutions. J Phys Chem B 2023; 127:809-821. [PMID: 36669139 DOI: 10.1021/acs.jpcb.2c06988] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Coulomb interactions play a crucial role in a wide array of processes in aqueous solutions but present conceptual and computational challenges to both theory and simulations. We review recent developments in an approach addressing these challenges─local molecular field (LMF) theory. LMF theory exploits an exact and physically suggestive separation of intermolecular Coulomb interactions into strong short-range and uniformly slowly varying long-range components. This allows us to accurately determine the averaged effects of the long-range components on the short-range structure using effective single particle fields and analytical corrections, greatly reducing the need for complex lattice summation techniques used in most standard approaches. The simplest use of these ideas in aqueous solutions leads to the short solvent (SS) model, where both solvent-solvent and solute-solvent Coulomb interactions have only short-range components. Here we use the SS model to give a simple description of pairing of nucleobases and biologically relevant ions in water.
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Affiliation(s)
- Ang Gao
- Department of Physics, Beijing University of Posts and Telecommunications, Beijing, China 100876
| | - Richard C Remsing
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, United States
| | - John D Weeks
- Institute for Physical Science and Technology and Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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8
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Brünig F, Daldrop JO, Netz RR. Pair-Reaction Dynamics in Water: Competition of Memory, Potential Shape, and Inertial Effects. J Phys Chem B 2022; 126:10295-10304. [PMID: 36473702 PMCID: PMC9761671 DOI: 10.1021/acs.jpcb.2c05923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 11/11/2022] [Indexed: 12/12/2022]
Abstract
When described by a one-dimensional reaction coordinate, pair-reaction rates in a solvent depend, in addition to the potential barrier height and the friction coefficient, on the potential shape, the effective mass, and the friction relaxation spectrum, but a rate theory that accurately accounts for all of these effects does not exist. After a review of classical reaction-rate theories, we show how to extract all parameters of the generalized Langevin equation (GLE) and, in particular, the friction memory function from molecular dynamics (MD) simulations of two prototypical pair reactions in water, the dissociation of NaCl and of two methane molecules. The memory exhibits multiple time scales and, for NaCl, pronounced oscillatory components. Simulations of the GLE by Markovian embedding techniques accurately reproduce the pair-reaction kinetics from MD simulations without any fitting parameters, which confirms the accuracy of the approximative form of the GLE and of the parameter extraction techniques. By modification of the GLE parameters, we investigate the relative importance of memory, mass, and potential shape effects. Neglect of memory slows down NaCl and methane dissociation by roughly a factor of 2; neglect of mass accelerates reactions by a similar factor, and the harmonic approximation of the potential shape gives rise to slight acceleration. This partial error cancellation explains why Kramers' theory, which neglects memory effects and treats the potential shape in harmonic approximation, describes reaction rates better than more sophisticated theories. In essence, all three effects, friction memory, inertia, and the potential shape nonharmonicity, are important to quantitatively describe pair-reaction kinetics in water.
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Affiliation(s)
- Florian
N. Brünig
- Fachbereich Physik, Freie Universität
Berlin, Arnimallee 14, 14195Berlin, Germany
| | - Jan O. Daldrop
- Fachbereich Physik, Freie Universität
Berlin, Arnimallee 14, 14195Berlin, Germany
| | - Roland R. Netz
- Fachbereich Physik, Freie Universität
Berlin, Arnimallee 14, 14195Berlin, Germany
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9
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Hasyim MR, Batton CH, Mandadapu KK. Supervised learning and the finite-temperature string method for computing committor functions and reaction rates. J Chem Phys 2022; 157:184111. [DOI: 10.1063/5.0102423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
A central object in the computational studies of rare events is the committor function. Though costly to compute, the committor function encodes complete mechanistic information of the processes involving rare events, including reaction rates and transition-state ensembles. Under the framework of transition path theory, Rotskoff et al. [ Proceedings of the 2nd Mathematical and Scientific Machine Learning Conference, Proceedings of Machine Learning Research (PLMR, 2022), Vol. 145, pp. 757–780] proposes an algorithm where a feedback loop couples a neural network that models the committor function with importance sampling, mainly umbrella sampling, which collects data needed for adaptive training. In this work, we show additional modifications are needed to improve the accuracy of the algorithm. The first modification adds elements of supervised learning, which allows the neural network to improve its prediction by fitting to sample-mean estimates of committor values obtained from short molecular dynamics trajectories. The second modification replaces the committor-based umbrella sampling with the finite-temperature string (FTS) method, which enables homogeneous sampling in regions where transition pathways are located. We test our modifications on low-dimensional systems with non-convex potential energy where reference solutions can be found via analytical or finite element methods, and show how combining supervised learning and the FTS method yields accurate computation of committor functions and reaction rates. We also provide an error analysis for algorithms that use the FTS method, using which reaction rates can be accurately estimated during training with a small number of samples. The methods are then applied to a molecular system in which no reference solution is known, where accurate computations of committor functions and reaction rates can still be obtained.
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Affiliation(s)
- Muhammad R. Hasyim
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
| | - Clay H. Batton
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
| | - Kranthi K. Mandadapu
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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10
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Yang X, Ji M, Zhang C, Yang X, Xu Z. Physical insight into the entropy-driven ion association. J Comput Chem 2022; 43:1621-1632. [PMID: 35801676 DOI: 10.1002/jcc.26963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/15/2022] [Accepted: 06/20/2022] [Indexed: 11/09/2022]
Abstract
The ion association is widely believed to be dominated by the favorable entropy change arising from the release of water molecules from ion hydration shells. However, no direct thermodynamic evidence exists to validate the reliability and suitability of this view. Herein, we employ complicated free energy calculations to rigorously split the free energy including its entropic and enthalpic components into the water-induced contributions and ion-ion interaction terms for several ion pairs from monatomic to polyatomic ions, spanning the size range from small kosmotropes to large chaotropes (Na+ , Cs+ , Ca2+ , F- , I- , CO3 2- , and HPO4 2- ). Our results successfully reveal that though ion associations are indeed determined by a delicate balance between the favorable entropy variation and the repulsive enthalpy change, the entropy gain dominated by the solvent occurs only for the monatomic ion pairing. The water-induced entropic contribution significantly goes against the ion pairing between polyatomic anion and cation, which is, alternatively, dominated by the favorable entropy from the ion-ion interaction term, due to the configurational arrangement of polyatomic anions involved in ion association. The structural and dynamic analysis demonstrates that the entropy penalty from the water phase is primarily ascribed to the enhanced stability of water molecules around the cation imposed by the incoming anion. Our study successfully provides a fundamental understanding of water-mediated ion associations and highlights disparate lengthscale dependencies of the dehydration thermodynamics on the specific types of ions.
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Affiliation(s)
- Xiao Yang
- College of Chemical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, China
| | - Mingyu Ji
- College of Chemical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, China
| | - Cong Zhang
- College of Chemical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, China
| | - Xiaoning Yang
- College of Chemical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, China
| | - Zhijun Xu
- College of Chemical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, China.,Zhangjiagang Institute of Nanjing Tech University, Zhangjiagang, China
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11
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Neumann J, Schwierz N. Artificial Intelligence Resolves Kinetic Pathways of Magnesium Binding to RNA. J Chem Theory Comput 2022; 18:1202-1212. [PMID: 35084846 PMCID: PMC8830046 DOI: 10.1021/acs.jctc.1c00752] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Magnesium is an indispensable cofactor in countless vital processes. In order to understand its functional role, the characterization of the binding pathways to biomolecules such as RNA is crucial. Despite the importance, a molecular description is still lacking since the transition from the water-mediated outer-sphere to the direct inner-sphere coordination is on the millisecond time scale and therefore out of reach for conventional simulation techniques. To fill this gap, we use transition path sampling to resolve the binding pathways and to elucidate the role of the solvent in the binding process. The results reveal that the molecular void provoked by the leaving phosphate oxygen of the RNA is immediately filled by an entering water molecule. In addition, water molecules from the first and second hydration shell couple to the concerted exchange. To capture the intimate solute-solvent coupling, we perform a committor analysis as the basis for a machine learning algorithm that derives the optimal deep learning model from thousands of scanned architectures using hyperparameter tuning. The results reveal that the properly optimized deep network architecture recognizes the important solvent structures, extracts the relevant information, and predicts the commitment probability with high accuracy. Our results provide detailed insights into the solute-solvent coupling which is ubiquitous for kosmotropic ions and governs a large variety of biochemical reactions in aqueous solutions.
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Affiliation(s)
- Jan Neumann
- Allianz Global Investors GmbH, Bockenheimer Landstrasse 42, 60323 Frankfurt am Main, Germany
| | - Nadine Schwierz
- Department of Theoretical Biophysics, Max-Planck-Institute of Biophysics, 60438 Frankfurt am Main, Germany
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12
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Wang D, Zhao R, Weeks JD, Tiwary P. Influence of Long-Range Forces on the Transition States and Dynamics of NaCl Ion-Pair Dissociation in Water. J Phys Chem B 2022; 126:545-551. [PMID: 34985884 DOI: 10.1021/acs.jpcb.1c09454] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We study NaCl ion-pair dissociation in a dilute aqueous solution using computer simulations both for the full system with long-range Coulomb interactions and for a well-chosen reference system with short-range intermolecular interactions. Analyzing results using concepts from Local Molecular Field (LMF) theory and the recently proposed AI-based analysis tool "State predictive information bottleneck" (SPIB), we show that the system with short-range interactions can accurately reproduce the transition rate for the dissociation process, the dynamics for moving between the underlying metastable states, and the transition state ensemble. Contributions from long-range interactions can be largely neglected for these processes because long-range forces from the direct interionic Coulomb interactions are almost completely canceled (>90%) by those from solvent interactions over the length scale where the transition takes place. Thus, for this important monovalent ion-pair system, short-range forces alone are able to capture detailed consequences of the collective solvent motion, allowing the use of physically suggestive and computationally efficient short-range models for the dissociation event. We believe that the framework here should be applicable to disentangling mechanisms for more complex processes such as multivalent ion disassociation, where previous work has suggested that long-range contributions may be more important.
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Affiliation(s)
- Dedi Wang
- Biophysics Program and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States
| | - Renjie Zhao
- Chemical Physics Program and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States
| | - John D Weeks
- Department of Chemistry and Biochemistry and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States
| | - Pratyush Tiwary
- Department of Chemistry and Biochemistry and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States
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13
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Anand S, Swami P, Goel G, Gupta S. Zwitterions for impedance spectroscopy: The new buffers in town. Anal Chim Acta 2021; 1166:338547. [PMID: 34022999 DOI: 10.1016/j.aca.2021.338547] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 04/03/2021] [Accepted: 04/05/2021] [Indexed: 11/29/2022]
Abstract
Studying the role of buffers in impedance spectroscopy is a relatively unexplored area. We demonstrate a special class of biologically relevant buffers known as Good's zwitterionic buffers that show improved performance over standard electrolyte buffers (e.g. PBS) currently widely used in impedance spectroscopy measurements of bacterial suspensions. Our theoretical and experimental comparisons of conductivity of classical and zwitterionic buffers at various different concentrations show that ion-ion interaction effects are significantly higher in zwitterionic buffers as compared to classical buffers at the concentrations at which they are used. This and the fact that zwitterions have larger sizes leads to the lowering of their conductivity which significantly improves their impedance sensing ability. We illustrate through an example of heat-induced ionic release in model S. typhi and S. aureus bacteria that having a low conductivity buffer is indeed beneficial for biological impedance measurements. In fact, the best buffer for impedance studies can be chosen solely based on their electrical properties as long as they are also biologically compatible. This gives Good's zwitterionic buffers an edge over conventional media as they satisfy both these criteria.
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Affiliation(s)
- Satyam Anand
- Dept. of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Pragya Swami
- Dept. of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Gaurav Goel
- Dept. of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi, 110016, India.
| | - Shalini Gupta
- Dept. of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi, 110016, India.
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14
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Singh D, Mondal K, Chaudhury S. Effect of Memory and Inertial Contribution on Transition-Time Distributions: Theory and Simulations. J Phys Chem B 2021; 125:4536-4545. [PMID: 33900087 DOI: 10.1021/acs.jpcb.1c00173] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Transition paths refer to the time taken by molecules to cross a barrier separating two molecular conformations. In this work, we study how memory, as well as inertial contribution in the dynamics along a reaction coordinate, can affect the distribution of the transition-path time. We use a simple model of dynamics governed by a generalized Langevin equation with a power-law memory along with the inertial term, which was neglected in previous studies, where memory effects were explored only in the overdamped limit. We derive an approximate expression for the transit-time distribution and discuss our results for the short- and long-time limits and also compare it with known results in the high friction (overdamped) limit as well as in the Markovian limit. We have developed a numerical algorithm to test our theoretical results against extensive numerical simulations.
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Affiliation(s)
- Divya Singh
- Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008, Maharashtra, India
| | - Kinjal Mondal
- Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008, Maharashtra, India
| | - Srabanti Chaudhury
- Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008, Maharashtra, India
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15
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Bolhuis PG, Swenson DWH. Transition Path Sampling as Markov Chain Monte Carlo of Trajectories: Recent Algorithms, Software, Applications, and Future Outlook. ADVANCED THEORY AND SIMULATIONS 2021. [DOI: 10.1002/adts.202000237] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Peter G. Bolhuis
- Amsterdam Center for Multiscale Modeling van 't Hoff Institute for Molecular Sciences University of Amsterdam PO Box 94157 1090 GD Amsterdam The Netherlands
| | - David W. H. Swenson
- Centre Blaise Pascal Ecole Normale Superieure 46, allée d'Italie 69364 Lyon Cedex 07 France
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16
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Niblett SP, Limmer DT. Ion Dissociation Dynamics in an Aqueous Premelting Layer. J Phys Chem B 2021; 125:2174-2181. [DOI: 10.1021/acs.jpcb.0c11286] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Samuel P. Niblett
- Materials Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720, United States
| | - David T. Limmer
- Chemistry Department, University of California, Berkeley, California 94720, United States
- Chemical Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720, United States
- Kavli Energy Nanosciences Institute, University of California, Berkeley, California 94720, United States
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17
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Zhang C, Giberti F, Sevgen E, de Pablo JJ, Gygi F, Galli G. Dissociation of salts in water under pressure. Nat Commun 2020; 11:3037. [PMID: 32546791 PMCID: PMC7298052 DOI: 10.1038/s41467-020-16704-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 05/15/2020] [Indexed: 11/09/2022] Open
Abstract
The investigation of salts in water at extreme conditions is crucial to understanding the properties of aqueous fluids in the Earth. We report first principles (FP) and classical molecular dynamics simulations of NaCl in the dilute limit, at temperatures and pressures relevant to the Earth’s upper mantle. Similar to ambient conditions, we observe two metastable states of the salt: the contact (CIP) and the solvent-shared ion-pair (SIP), which are entropically and enthalpically favored, respectively. We find that the free energy barrier between the CIP and SIP minima increases at extreme conditions, and that the stability of the CIP is enhanced in FP simulations, consistent with the decrease of the dielectric constant of water. The minimum free energy path between the CIP and SIP becomes smoother at high pressure, and the relative stability of the two configurations is affected by water self-dissociation, which can only be described properly by FP simulations. Salts in water at extreme conditions play a fundamental role in determining the properties of the Earthʼs mantle constituents. Here the authors shed light on ion-water and ion-ion interactions for NaCl dissolved in water at conditions relevant to the Earthʼs upper mantle by molecular dynamics simulations.
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Affiliation(s)
- Cunzhi Zhang
- Department of Materials Science and Engineering, COE, Peking University, 100871, Beijing, China
| | - Federico Giberti
- University of Chicago, 5640 S. Ellis Ave., Chicago, IL, 60637, USA
| | - Emre Sevgen
- University of Chicago, 5640 S. Ellis Ave., Chicago, IL, 60637, USA
| | - Juan J de Pablo
- University of Chicago, 5640 S. Ellis Ave., Chicago, IL, 60637, USA.,Materials Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Francois Gygi
- University of California Davis, Davis, CA, 95616, USA
| | - Giulia Galli
- University of Chicago, 5640 S. Ellis Ave., Chicago, IL, 60637, USA. .,Materials Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA.
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18
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Ramamoorthy RK, Levesque M, Belloni L, Carriere D. Structure Factor of EuCl 3 Aqueous Solutions via Coupled Molecular Dynamics Simulations and Integral Equations. J Phys Chem B 2020; 124:1787-1793. [PMID: 32026687 DOI: 10.1021/acs.jpcb.9b11537] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Identifying the structure of an aqueous solution is essential to rationalize various phenomena such as crystallization in solution, chemical reactivity, extraction of rare earth elements, and so forth. Despite this, the efforts to describe the structure of an aqueous solution have been hindered by the difficulty to retrieve structural data both from experiments and simulations. To overcome this, first, undersaturated EuCl3 aqueous solutions of concentrations varying from 0.15 to 1.8 mol/kg were studied using X-ray scattering. Second, for the first time, the theoretical X-ray signal of 1.8 mol/kg EuCl3 aqueous solution was simulated, with precise details for the complete range of scattering vectors using coupled molecular dynamics and hypernetted chain integral equations, and satisfactorily compared with the 1.8 mol/kg experimental X-ray scattering signal. The theoretical calculations demonstrate that the experimental structure factor is dominated by Eu3+-Eu3+ correlations.
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Affiliation(s)
| | - Maximilien Levesque
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Luc Belloni
- Université Paris-Saclay, CEA, CNRS, NIMBE, LIONS, 91191 Gif-sur-Yvette, France
| | - David Carriere
- Université Paris-Saclay, CEA, CNRS, NIMBE, LIONS, 91191 Gif-sur-Yvette, France
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19
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Abstract
Coulomb interactions play a major role in determining the thermodynamics, structure, and dynamics of condensed-phase systems, but often present significant challenges. Computer simulations usually use periodic boundary conditions to minimize corrections from finite cell boundaries but the long range of the Coulomb interactions generates significant contributions from distant periodic images of the simulation cell, usually calculated by Ewald sum techniques. This can add significant overhead to computer simulations and hampers the development of intuitive local pictures and simple analytic theory. In this paper, we present a general framework based on local molecular field theory to accurately determine the contributions from long-ranged Coulomb interactions to the potential of mean force between ionic or apolar hydrophobic solutes in dilute aqueous solutions described by standard classical point charge water models. The simplest approximation leads to a short solvent (SS) model, with truncated solvent-solvent and solute-solvent Coulomb interactions and long-ranged but screened Coulomb interactions only between charged solutes. The SS model accurately describes the interplay between strong short-ranged solute core interactions, local hydrogen-bond configurations, and long-ranged dielectric screening of distant charges, competing effects that are difficult to capture in standard implicit solvent models.
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20
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Crundwell FK. The impact of surface charge on the ionic dissociation of common salt (NaCl). Chem Eng Sci 2019. [DOI: 10.1016/j.ces.2019.04.050] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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Schile AJ, Limmer DT. Rate constants in spatially inhomogeneous systems. J Chem Phys 2019; 150:191102. [DOI: 10.1063/1.5092837] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Addison J. Schile
- Department of Chemistry, University of California, Berkeley, California 94720-1460, USA
- Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720-1460, USA
| | - David T. Limmer
- Department of Chemistry, University of California, Berkeley, California 94720-1460, USA
- Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720-1460, USA
- Kavli Energy NanoSciences Institute, University of California, Berkeley, California 94720-1460, USA
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22
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Oh MI, Gupta M, Weaver DF. Understanding Water Structure in an Ion-Pair Solvation Shell in the Vicinity of a Water/Membrane Interface. J Phys Chem B 2019; 123:3945-3954. [DOI: 10.1021/acs.jpcb.9b01331] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Myong In Oh
- Krembil Research Institute, University Health Network, Toronto, Ontario M5T 0S8, Canada
| | - Mayuri Gupta
- Krembil Research Institute, University Health Network, Toronto, Ontario M5T 0S8, Canada
| | - Donald F. Weaver
- Krembil Research Institute, University Health Network, Toronto, Ontario M5T 0S8, Canada
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
- Department of Medicine, University of Toronto, Toronto, Ontario M5G 2C4, Canada
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario M5S 3M2, Canada
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23
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Blasius J, Ingenmey J, Perlt E, von Domaros M, Hollóczki O, Kirchner B. Predicting Mole-Fraction-Dependent Dissociation for Weak Acids. Angew Chem Int Ed Engl 2019; 58:3212-3216. [PMID: 30589171 DOI: 10.1002/anie.201811839] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/12/2018] [Indexed: 11/10/2022]
Abstract
We demonstrate for formic and acetic acid dissolved in water as examples that the binary quantum cluster equilibrium (bQCE) approach can predict acid strengths over the whole range of acid concentrations. The acid strength increases in a complex rather than a simple way with increasing mole fraction of the acid from 0 to 0.7, reflecting the complex interplay between the dissociated ions or conjugate bases available as compared to the acid and water molecules. Furthermore, our calculated ion concentrations meet the experimental maximum of the conductivity with excellent agreement for acetic acid and satisfactorily for the formic acid/water mixture. As only a limited number of simple quantum-chemical calculations are required for the prediction, bQCE is clearly a valuable approach to access these quantities also in non-aqueous solutions. It is a highly valuable asset for predicting ionization processes in highly concentrated solutions, which are relevant for biological and chemical systems, as well as technological processes.
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Affiliation(s)
- Jan Blasius
- Mulliken Center for Theoretical Chemistry, Universität Bonn, Beringstr. 4, 53115, Bonn, Germany
| | - Johannes Ingenmey
- Mulliken Center for Theoretical Chemistry, Universität Bonn, Beringstr. 4, 53115, Bonn, Germany
| | - Eva Perlt
- Department of Chemistry, 1102 Natural Sciences II, University of California, Irvine, Irvine, CA, 92697, USA
| | - Michael von Domaros
- Department of Chemistry, 1102 Natural Sciences II, University of California, Irvine, Irvine, CA, 92697, USA
| | - Oldamur Hollóczki
- Mulliken Center for Theoretical Chemistry, Universität Bonn, Beringstr. 4, 53115, Bonn, Germany
| | - Barbara Kirchner
- Mulliken Center for Theoretical Chemistry, Universität Bonn, Beringstr. 4, 53115, Bonn, Germany
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24
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Blasius J, Ingenmey J, Perlt E, von Domaros M, Hollóczki O, Kirchner B. Dissoziation schwacher Säuren über den gesamten Molenbruchbereich. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201811839] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Jan Blasius
- Mulliken Center for Theoretical ChemistryUniversität Bonn Beringstraße 4 53115 Bonn Deutschland
| | - Johannes Ingenmey
- Mulliken Center for Theoretical ChemistryUniversität Bonn Beringstraße 4 53115 Bonn Deutschland
| | - Eva Perlt
- Department of Chemistry, 1102Natural Sciences IIUniversity of California, Irvine Irvine CA 92697 USA
| | - Michael von Domaros
- Department of Chemistry, 1102Natural Sciences IIUniversity of California, Irvine Irvine CA 92697 USA
| | - Oldamur Hollóczki
- Mulliken Center for Theoretical ChemistryUniversität Bonn Beringstraße 4 53115 Bonn Deutschland
| | - Barbara Kirchner
- Mulliken Center for Theoretical ChemistryUniversität Bonn Beringstraße 4 53115 Bonn Deutschland
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25
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On the ion‐pair dissociation mechanisms in the small NaCl·(H
2
O)
6
cluster: A perspective from reaction path search calculations. J Comput Chem 2018; 39:1835-1842. [DOI: 10.1002/jcc.25227] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 03/24/2018] [Accepted: 03/27/2018] [Indexed: 11/07/2022]
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26
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Salanne M, Tazi S, Vuilleumier R, Rotenberg B. Ca 2+ -Cl - Association in Water Revisited: the Role of Cation Hydration. Chemphyschem 2017; 18:2807-2811. [PMID: 28510283 DOI: 10.1002/cphc.201700286] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 05/16/2017] [Indexed: 11/08/2022]
Abstract
We investigate the dissociation of a Ca2+ -Cl- pair in water using classical molecular dynamics simulations with a polarizable interaction potential, parameterized from ab initio calculations. By computing the potential of mean force as a function not only of the interionic distance but also of the coordination numbers by water molecules, we show that it is necessary to use a collective variable describing the cation hydration in order to capture the dissociation mechanism. In the contact ion pair, the Ca2+ cation has a first coordination sphere containing 5 or 6 water molecules. The minimum free-energy path for dissociation involves a two-step process: First one or two additional water molecules enter the cation coordination shell, increasing the coordination number up to 7 with an almost fixed interionic distance. Then the dissociation of the ionic pair occurs at this fixed coordination number.
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Affiliation(s)
- Mathieu Salanne
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8234 PHENIX, 4 Place Jussieu, 75005, Paris, France
| | - Sami Tazi
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8234 PHENIX, 4 Place Jussieu, 75005, Paris, France
| | - Rodolphe Vuilleumier
- Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, PASTEUR, 75005, Paris, France
| | - Benjamin Rotenberg
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8234 PHENIX, 4 Place Jussieu, 75005, Paris, France
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27
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Alaghemandi M, Koller V, Green JR. Nonexponential kinetics of ion pair dissociation in electrofreezing water. Phys Chem Chem Phys 2017; 19:26396-26402. [PMID: 28944386 DOI: 10.1039/c7cp04572g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Temporally- or spatially-heterogeneous environments can participate in many kinetic processes, from chemical reactions and self-assembly to the forced dissociation of biomolecules. Here, we simulate the molecular dynamics of a model ion pair forced to dissociate in an explicit, aqueous solution. Triggering dissociation with an external electric field causes the surrounding water to electrofreeze and the ion pair population to decay nonexponentially. To further probe the role of the aqueous environment in the kinetics, we also simulate dissociation events under a purely mechanical force on the ion pair. In this case, regardless of whether the surrounding water is a liquid or already electrofrozen, the ion pair population decays exponentially with a well-defined rate constant that is specific to the medium and applied force. These simulation data, and the rate parameters we extract, suggest the disordered kinetics in an electrofreezing medium are a result of the comparable time scales of two concurrent processes, electrofreezing and dissociation.
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Affiliation(s)
- Mohammad Alaghemandi
- Department of Chemistry, University of Massachusetts Boston, Boston, MA 02125, USA.
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28
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Microscopic dynamics of charge separation at the aqueous electrochemical interface. Proc Natl Acad Sci U S A 2017; 114:13374-13379. [PMID: 28698368 DOI: 10.1073/pnas.1700093114] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have used molecular simulation and methods of importance sampling to study the thermodynamics and kinetics of ionic charge separation at a liquid water-metal interface. We have considered this process using canonical examples of two different classes of ions: a simple alkali-halide pair, Na+I-, or classical ions, and the products of water autoionization, H3O+OH-, or water ions. We find that for both ion classes, the microscopic mechanism of charge separation, including water's collective role in the process, is conserved between the bulk liquid and the electrode interface. However, the thermodynamic and kinetic details of the process differ between these two environments in a way that depends on ion type. In the case of the classical ion pairs, a higher free-energy barrier to charge separation and a smaller flux over that barrier at the interface result in a rate of dissociation that is 40 times slower relative to the bulk. For water ions, a slightly higher free-energy barrier is offset by a higher flux over the barrier from longer lived hydrogen-bonding patterns at the interface, resulting in a rate of association that is similar both at and away from the interface. We find that these differences in rates and stabilities of charge separation are due to the altered ability of water to solvate and reorganize in the vicinity of the metal interface.
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29
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Affiliation(s)
- Yoshiteru Yonetani
- Quantum Beam Science Research Directorate, National Institute for Quantum and Radiological Science and Technology (QST), Tokai-mura, Ibaraki, Japan
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30
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Shi Y, Beck T. Deconstructing Free Energies in the Law of Matching Water Affinities. J Phys Chem B 2017; 121:2189-2201. [DOI: 10.1021/acs.jpcb.7b00104] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yu Shi
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Thomas Beck
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
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31
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Carof A, Salanne M, Charpentier T, Rotenberg B. On the microscopic fluctuations driving the NMR relaxation of quadrupolar ions in water. J Chem Phys 2016; 143:194504. [PMID: 26590539 DOI: 10.1063/1.4935496] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Nuclear Magnetic Resonance (NMR) relaxation is sensitive to the local structure and dynamics around the probed nuclei. The Electric Field Gradient (EFG) is the key microscopic quantity to understand the NMR relaxation of quadrupolar ions, such as (7)Li(+), (23)Na(+), (25)Mg(2+), (35)Cl(-), (39)K(+), or (133)Cs(+). Using molecular dynamics simulations, we investigate the statistical and dynamical properties of the EFG experienced by alkaline, alkaline Earth, and chloride ions at infinite dilution in water. Specifically, we analyze the effect of the ionic charge and size on the distribution of the EFG tensor and on the multi-step decay of its auto-correlation function. The main contribution to the NMR relaxation time arises from the slowest mode, with a characteristic time on the picosecond time scale. The first solvation shell of the ion plays a dominant role in the fluctuations of the EFG, all the more that the ion radius is small and its charge is large. We propose an analysis based on a simplified charge distribution around the ion, which demonstrates that the auto-correlation of the EFG, hence the NMR relaxation time, reflects primarily the collective translational motion of water molecules in the first solvation shell of the cations. Our findings provide a microscopic route to the quantitative interpretation of NMR relaxation measurements and open the way to the design of improved analytical theories for NMR relaxation for small ionic solutes, which should focus on water density fluctuations around the ion.
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Affiliation(s)
- Antoine Carof
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Laboratoire PHENIX, Case 51, 4 Place Jussieu, F-75005 Paris, France
| | - Mathieu Salanne
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Laboratoire PHENIX, Case 51, 4 Place Jussieu, F-75005 Paris, France
| | - Thibault Charpentier
- CEA, IRAMIS, NIMBE, LSDRM, UMR CEA-CNRS 3685, F-91191 Gif-sur-Yvette Cedex, France
| | - Benjamin Rotenberg
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Laboratoire PHENIX, Case 51, 4 Place Jussieu, F-75005 Paris, France
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32
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Mehandzhiyski AY, Grimes BA. Calculation of the probability for ionic association and dissociation reactions by molecular dynamics and umbrella sampling. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1155776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
| | - Brian A. Grimes
- Department of Chemical Engineering, Norwegian University of Science and Technology, Trondheim, Norway
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33
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Duignan TT, Parsons DF, Ninham BW. A continuum solvent model of ion-ion interactions in water. Phys Chem Chem Phys 2015; 16:22014-27. [PMID: 25205066 DOI: 10.1039/c4cp02822h] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The calculation of ion-ion interactions in water is a problem of long standing importance. Modelling these interactions is a prerequisite to explaining Hofmeister (specific ion) effects. We here generalize our solvation model of ions to calculate the free energy of two ions in water as a function of separation. The same procedure has previously been applied to calculate ion interactions with the air-water interface successfully. The Conductor like Screening Model (COSMO) is used. This treats the ions on a quantum mechanical level and calculates numerically the electrostatic response of the surrounding solvent. Estimates of the change in the cavity formation energy and the change in the ion-water dispersion energy as the ions approach are included separately. The calculated interaction potentials are too attractive and this is a significant issue. However, they do reproduce the affinity of similarly sized ions for each other, which is a crucial property of these potentials. They are also oscillatory, another important property. We normalize the potentials to reduce the over-attraction, and good correlation with experimental values is achieved. We identify the driving contributions to this like-prefers-like behaviour. We then put forward a plausible hypothesis for the over-attraction of the potentials. An agreeable feature of our approach is that it does not rely on salt specific parameters deliberately adjusted to reproduce experimental values.
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Affiliation(s)
- Timothy T Duignan
- Applied Mathematics Department, Australian National University, Canberra, ACT 0200, Australia.
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34
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Zinovjev K, Tuñón I. Transition state ensemble optimization for reactions of arbitrary complexity. J Chem Phys 2015; 143:134111. [DOI: 10.1063/1.4931596] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Affiliation(s)
- Kirill Zinovjev
- Departament de Química Física, Universitat de València, 46100 Burjassot, Spain
| | - Iñaki Tuñón
- Departament de Química Física, Universitat de València, 46100 Burjassot, Spain
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35
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Mehandzhiyski AY, Riccardi E, van Erp TS, Trinh TT, Grimes BA. Ab Initio Molecular Dynamics Study on the Interactions between Carboxylate Ions and Metal Ions in Water. J Phys Chem B 2015; 119:10710-9. [DOI: 10.1021/acs.jpcb.5b05616] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Aleksandar Y. Mehandzhiyski
- Ugelstad
Laboratory, Department of Chemical Engineering, Norwegian University of Science and Technology, SemSælandsvei 4, NO-7491 Trondheim, Norway
| | - Enrico Riccardi
- Department
of Chemistry, Norwegian University of Science and Technology, Høgskoleringen
5 Realfagbygget blokk D, 3.etg., NO-7491 Trondheim, Norway
| | - Titus S. van Erp
- Department
of Chemistry, Norwegian University of Science and Technology, Høgskoleringen
5 Realfagbygget blokk D, 3.etg., NO-7491 Trondheim, Norway
| | - Thuat T. Trinh
- Department
of Chemistry, Norwegian University of Science and Technology, Høgskoleringen
5 Realfagbygget blokk D, 3.etg., NO-7491 Trondheim, Norway
| | - Brian A. Grimes
- Ugelstad
Laboratory, Department of Chemical Engineering, Norwegian University of Science and Technology, SemSælandsvei 4, NO-7491 Trondheim, Norway
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36
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Yonetani Y. Distinct dissociation kinetics between ion pairs: Solvent-coordinate free-energy landscape analysis. J Chem Phys 2015; 143:044506. [DOI: 10.1063/1.4927093] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yoshiteru Yonetani
- Quantum Beam Science Center, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan
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37
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Mullen RG, Shea JE, Peters B. Easy Transition Path Sampling Methods: Flexible-Length Aimless Shooting and Permutation Shooting. J Chem Theory Comput 2015; 11:2421-8. [DOI: 10.1021/acs.jctc.5b00032] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ryan Gotchy Mullen
- Department of Chemical Engineering, ‡Department of Chemistry & Biochemistry, §Department of Physics, University of California, Santa Barbara, California 93106, United States
| | - Joan-Emma Shea
- Department of Chemical Engineering, ‡Department of Chemistry & Biochemistry, §Department of Physics, University of California, Santa Barbara, California 93106, United States
| | - Baron Peters
- Department of Chemical Engineering, ‡Department of Chemistry & Biochemistry, §Department of Physics, University of California, Santa Barbara, California 93106, United States
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38
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Affiliation(s)
- Baron Peters
- Department
of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Department
of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
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39
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Chen JC, Reischl B, Spijker P, Holmberg N, Laasonen K, Foster AS. Ab initio Kinetic Monte Carlo simulations of dissolution at the NaCl-water interface. Phys Chem Chem Phys 2014; 16:22545-54. [PMID: 25227553 DOI: 10.1039/c4cp02375g] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have used ab initio molecular dynamics (AIMD) simulations to study the interaction of water with the NaCl surface. As expected, we find that water forms several ordered hydration layers, with the first hydration layer having water molecules aligned so that oxygen atoms are on average situated above Na sites. In an attempt to understand the dissolution of NaCl in water, we have then combined AIMD with constrained barrier searches, to calculate the dissolution energetics of Na(+) and Cl(-) ions from terraces, steps, corners and kinks of the (100) surface. We find that the barrier heights show a systematic reduction from the most stable flat terrace sites, through steps to the smallest barriers for corner and kink sites. Generally, the barriers for removal of Na(+) ions are slightly lower than for Cl(-) ions. Finally, we use our calculated barriers in a Kinetic Monte Carlo as a first order model of the dissolution process.
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Affiliation(s)
- Jian-Cheng Chen
- COMP Centre of Excellence and Department of Applied Physics, Aalto University, FI-00076 Helsinki, Finland.
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40
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Annapureddy HVR, Dang LX. Understanding the rates and molecular mechanism of water-exchange around aqueous ions using molecular simulations. J Phys Chem B 2014; 118:8917-27. [PMID: 24911526 DOI: 10.1021/jp502922c] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Solvation processes occurring around aqueous ions are of fundamental importance in physics, chemistry, and biology. Over the past few decades, several experimental and theoretical studies were devoted to understanding ion solvation and the processes involved in it. In this article, we present a summary of our recent efforts that, through computer simulations, focused on providing a comprehensive understanding of solvent-exchange processes around aqueous ions. To accomplish these activities, we have looked at the mechanistic properties associated with the water-exchange process, such as potentials of mean force, time-dependent transmission coefficients, and the corresponding rate constants using transition state theory, the reactive flux method, and Grote-Hynes treatments of the dynamic response of the solvent.
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Affiliation(s)
- Harsha V R Annapureddy
- Physical Sciences Division, Pacific Northwest National Laboratory , Richland, Washington 93352, United States
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Mullen RG, Shea JE, Peters B. Transmission Coefficients, Committors, and Solvent Coordinates in Ion-Pair Dissociation. J Chem Theory Comput 2014; 10:659-67. [DOI: 10.1021/ct4009798] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ryan Gotchy Mullen
- Department of Chemical Engineering, ‡Department of Chemistry & Biochemistry, §Department of Physics, University of California, Santa Barbara, California 93106
| | - Joan-Emma Shea
- Department of Chemical Engineering, ‡Department of Chemistry & Biochemistry, §Department of Physics, University of California, Santa Barbara, California 93106
| | - Baron Peters
- Department of Chemical Engineering, ‡Department of Chemistry & Biochemistry, §Department of Physics, University of California, Santa Barbara, California 93106
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Mullen RG, Shea JE, Peters B. Communication: An existence test for dividing surfaces without recrossing. J Chem Phys 2014; 140:041104. [DOI: 10.1063/1.4862504] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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43
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Holmberg N, Chen JC, Foster AS, Laasonen K. Dissolution of NaCl nanocrystals: an ab initio molecular dynamics study. Phys Chem Chem Phys 2014; 16:17437-46. [DOI: 10.1039/c4cp00635f] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
NaCl nanocrystal dissolution was investigated in atomistic detail revealing a difference in the solvation of two different ionic species.
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Affiliation(s)
- Nico Holmberg
- Department of Chemistry
- Aalto University
- FI-00076 Aalto, Finland
| | - Jian-Cheng Chen
- Department of Applied Physics
- Aalto University
- FI-00076 Aalto, Finland
- COMP Centre of Excellence in Computational Nanoscience
- Aalto University
| | - Adam S. Foster
- Department of Applied Physics
- Aalto University
- FI-00076 Aalto, Finland
- COMP Centre of Excellence in Computational Nanoscience
- Aalto University
| | - Kari Laasonen
- Department of Chemistry
- Aalto University
- FI-00076 Aalto, Finland
- COMP Centre of Excellence in Computational Nanoscience
- Aalto University
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44
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Knott BC, Haddad Momeni M, Crowley MF, Mackenzie LF, Götz AW, Sandgren M, Withers SG, Ståhlberg J, Beckham GT. The Mechanism of Cellulose Hydrolysis by a Two-Step, Retaining Cellobiohydrolase Elucidated by Structural and Transition Path Sampling Studies. J Am Chem Soc 2013; 136:321-9. [DOI: 10.1021/ja410291u] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
| | - Majid Haddad Momeni
- Department
of Molecular Biology, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
| | | | - Lloyd F. Mackenzie
- Department
of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1
| | - Andreas W. Götz
- San
Diego Supercomputer Center, University of California San Diego, La Jolla, California 92093, United States
| | - Mats Sandgren
- Department
of Molecular Biology, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
| | - Stephen G. Withers
- Department
of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1
| | - Jerry Ståhlberg
- Department
of Molecular Biology, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
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Sumikama T, Saito S, Ohmine I. Mechanism of ion permeation through a model channel: Roles of energetic and entropic contributions. J Chem Phys 2013; 139:165106. [DOI: 10.1063/1.4827088] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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