1
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Ravindra P, Advincula XR, Schran C, Michaelides A, Kapil V. Quasi-one-dimensional hydrogen bonding in nanoconfined ice. Nat Commun 2024; 15:7301. [PMID: 39181894 PMCID: PMC11344787 DOI: 10.1038/s41467-024-51124-z] [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: 12/31/2023] [Accepted: 07/30/2024] [Indexed: 08/27/2024] Open
Abstract
The Bernal-Fowler ice rules stipulate that each water molecule in an ice crystal should form four hydrogen bonds. However, in extreme or constrained conditions, the arrangement of water molecules deviates from conventional ice rules, resulting in properties significantly different from bulk water. In this study, we employ machine learning-driven first-principles simulations to identify a new stabilization mechanism in nanoconfined ice phases. Instead of forming four hydrogen bonds, nanoconfined crystalline ice can form a quasi-one-dimensional hydrogen-bonded structure that exhibits only two hydrogen bonds per water molecule. These structures consist of strongly hydrogen-bonded linear chains of water molecules that zig-zag along one dimension, stabilized by van der Waals interactions that stack these chains along the other dimension. The unusual interplay of hydrogen bonding and van der Waals interactions in nanoconfined ice results in atypical proton behavior such as potential ferroelectric behavior, low dielectric response, and long-range proton dynamics.
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Affiliation(s)
- Pavan Ravindra
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
- Department of Chemistry, Columbia University, 3000 Broadway, New York, NY, 10027, USA
| | - Xavier R Advincula
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE, UK
- Lennard-Jones Centre, University of Cambridge, Trinity Ln, Cambridge, CB2 1TN, UK
| | - Christoph Schran
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE, UK
- Lennard-Jones Centre, University of Cambridge, Trinity Ln, Cambridge, CB2 1TN, UK
| | - Angelos Michaelides
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
- Lennard-Jones Centre, University of Cambridge, Trinity Ln, Cambridge, CB2 1TN, UK.
| | - Venkat Kapil
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
- Lennard-Jones Centre, University of Cambridge, Trinity Ln, Cambridge, CB2 1TN, UK.
- Department of Physics and Astronomy, University College London, 17-19 Gordon St, London, WC1H 0AH, UK.
- Thomas Young Centre and London Centre for Nanotechnology, 19 Gordon St, London, WC1H 0AH, UK.
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2
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Huang Y, Yu F, Yang X, Wang L, Lü W. Design and Realization of Visual and Contact-Type Fast Charging Power Source. Chemistry 2024:e202402020. [PMID: 38981857 DOI: 10.1002/chem.202402020] [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: 05/23/2024] [Revised: 06/29/2024] [Accepted: 07/08/2024] [Indexed: 07/11/2024]
Abstract
Charging power supplies with both fast and visualization functions have a wide range of applications in the information and new energy industries. In this paper, the visualized and contact-type fast charging power supply based on WO3 film and Zn sheet is presented, and the prototype devices are fabricated. Different with the charging method of conventional batteries, charging is achieved by a Zn sheet contacting with a WO3 film moistened with water, resulting in a rapid discoloration of WO3. Theoretical investigation indicates that the interaction between Zn sheet and water molecules is the primary cause of the color change in the WO3 film. The WO3 film completes the colouring state within 10 s in the presence of Zn sheet and water, and the open-circuit voltage of the device is 0.7 V, which can be used to drive various electronics by series-parallel connection. This research introduces a novel method to induce colouring of WO3 films and proposes a fast charging mode different from traditional power sources. It provides valuable insights for the future development of fast charging in the field of electrical energy.
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Affiliation(s)
- Yuxin Huang
- Key Laboratory of Advanced Structural Materials, Ministry of Education & Advanced Institute of Materials Science, Changchun University of Technology, Changchun, 130012, People's Republic of China
| | - Fei Yu
- Key Laboratory of Advanced Structural Materials, Ministry of Education & Advanced Institute of Materials Science, Changchun University of Technology, Changchun, 130012, People's Republic of China
| | - Xijia Yang
- Key Laboratory of Advanced Structural Materials, Ministry of Education & Advanced Institute of Materials Science, Changchun University of Technology, Changchun, 130012, People's Republic of China
| | - Liying Wang
- Key Laboratory of Advanced Structural Materials, Ministry of Education & Advanced Institute of Materials Science, Changchun University of Technology, Changchun, 130012, People's Republic of China
| | - Wei Lü
- Key Laboratory of Advanced Structural Materials, Ministry of Education & Advanced Institute of Materials Science, Changchun University of Technology, Changchun, 130012, People's Republic of China
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033, People's Republic of China
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3
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Noetzel J, Schienbein P, Forbert H, Marx D. Solvation Properties of Neutral Gold Species in Supercritical Water Studied By THz Spectroscopy. Angew Chem Int Ed Engl 2024; 63:e202402120. [PMID: 38695846 DOI: 10.1002/anie.202402120] [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: 01/30/2024] [Indexed: 06/05/2024]
Abstract
Supercritical water provides distinctly different solvation properties compared to what is known from liquid water. Despite its prevalence deep in the Earth's crust and its role in chemosynthetic ecosystems in the vicinity of hydrothermal vents, molecular insights into its solvation mechanisms are still very scarce compared to what is known for liquid water. Recently, neutral metal particles have been detected in hydrothermal fluids and proposed to explain the transport of gold species to ore deposits on Earth. Using ab initio molecular dynamics, we elucidate the solvation properties of small gold species at supercritical conditions. The neutral metal clusters themselves contribute enormous THz intensity not because of their intramolecular vibrations, but due to their pronounced electronic polarization coupling to the dynamical supercritical solvent, leading to a continuum absorption up to about 1000 cm-1. On top, long-lived interactions between the gold clusters and solvation water leads at these supercritical conditions to a sharp THz resonance that happens to be close to the one due to H-bonding in liquid water at ambient conditions. The resulting distinct resonances can be used to analyse the solvation properties of neutral metal particles in supercritical aqueous solutions.
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Affiliation(s)
- Jan Noetzel
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, D-44780, Bochum
| | - Philipp Schienbein
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, D-44780, Bochum
- Present Address, Department of Physics, Imperial College London, Exhibition Rd, South Kensington, London, SW7 2AZ, United Kingdom
| | - Harald Forbert
- Center for Solvation Science ZEMOS, Ruhr-Universität Bochum, D-44780, Bochum
| | - Dominik Marx
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, D-44780, Bochum
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4
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Assomo JGGN, Ebrahimi S, Jay-Gerin JP, Soldera A. Supercritical Water: A Simulation Study to Unravel the Heterogeneity of Its Molecular Structures. Molecules 2024; 29:2947. [PMID: 38931011 PMCID: PMC11206336 DOI: 10.3390/molecules29122947] [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: 05/13/2024] [Revised: 06/14/2024] [Accepted: 06/19/2024] [Indexed: 06/28/2024] Open
Abstract
(1) Background: In the quest to accurately model the radiolysis of water in its supercritical state, a detailed understanding of water's molecular structure, particularly how water molecules are arranged in this unique state, is essential. (2) Methods: We conducted molecular dynamics simulations using the SPC/E water model to investigate the molecular structures of supercritical water (SCW) over a wide temperature range, extending up to 800 °C. (3) Results: Our results show that at a constant pressure of 25 MPa, the average intermolecular distance around a reference water molecule remains remarkably stable at ~2.9 Å. This uniformity persists across a substantial temperature range, demonstrating the unique heterogeneous nature of SCW under these extreme conditions. Notably, the simulations also reveal intricate patterns within SCW, indicating the simultaneous presence of regions with high and low density. As temperatures increase, we observe a rise in the formation of molecular clusters, which are accompanied by a reduction in their average size. (4) Conclusions: These findings highlight the necessity of incorporating the molecular complexity of SCW into traditional track-structure chemistry models to improve predictions of SCW behavior under ionizing radiation. The study establishes a foundational reference for further exploration of the properties of supercritical water, particularly for its application in advanced nuclear technologies, including the next generation of water-cooled reactors and their small modular reactor variants that utilize SCW as a coolant.
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Affiliation(s)
- Joseph Guy Gérard Ndongo Assomo
- Département de Physique, Faculté des Sciences, Université de Maroua, Maroua BP 814, Cameroon;
- Laboratory of Physical Chemistry of Matter (LPCM), Department of Chemistry, Faculty of Sciences, Université de Sherbrooke, 2500 Boulevard de l’Université, Sherbrooke, QC J1K 2R1, Canada;
- Department of Medical Imaging and Radiation Sciences, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001, 12th Avenue Nord, Sherbrooke, QC J1H 5N4, Canada;
| | - Sadollah Ebrahimi
- Laboratory of Physical Chemistry of Matter (LPCM), Department of Chemistry, Faculty of Sciences, Université de Sherbrooke, 2500 Boulevard de l’Université, Sherbrooke, QC J1K 2R1, Canada;
| | - Jean-Paul Jay-Gerin
- Department of Medical Imaging and Radiation Sciences, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001, 12th Avenue Nord, Sherbrooke, QC J1H 5N4, Canada;
| | - Armand Soldera
- Laboratory of Physical Chemistry of Matter (LPCM), Department of Chemistry, Faculty of Sciences, Université de Sherbrooke, 2500 Boulevard de l’Université, Sherbrooke, QC J1K 2R1, Canada;
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5
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Simeski F, Ihme M. Supercritical fluids behave as complex networks. Nat Commun 2023; 14:1996. [PMID: 37032390 PMCID: PMC10083177 DOI: 10.1038/s41467-023-37645-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 03/22/2023] [Indexed: 04/11/2023] Open
Abstract
Supercritical fluids play a key role in environmental, geological, and celestial processes, and are of great importance to many scientific and engineering applications. They exhibit strong variations in thermodynamic response functions, which has been hypothesized to stem from the microstructural behavior. However, a direct connection between thermodynamic conditions and the microstructural behavior, as described by molecular clusters, remains an outstanding issue. By utilizing a first-principles-based criterion and self-similarity analysis, we identify energetically localized molecular clusters whose size distribution and connectivity exhibit self-similarity in the extended supercritical phase space. We show that the structural response of these clusters follows a complex network behavior whose dynamics arises from the energetics of isotropic molecular interactions. Furthermore, we demonstrate that a hidden variable network model can accurately describe the structural and dynamical response of supercritical fluids. These results highlight the need for constitutive models and provide a basis to relate the fluid microstructure to thermodynamic response functions.
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Affiliation(s)
- Filip Simeski
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Matthias Ihme
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA.
- Department of Photon Science, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
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6
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Schienbein P. Spectroscopy from Machine Learning by Accurately Representing the Atomic Polar Tensor. J Chem Theory Comput 2023; 19:705-712. [PMID: 36695707 PMCID: PMC9933433 DOI: 10.1021/acs.jctc.2c00788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Vibrational spectroscopy is a key technique to elucidate microscopic structure and dynamics. Without the aid of theoretical approaches, it is, however, often difficult to understand such spectra at a microscopic level. Ab initio molecular dynamics has repeatedly proved to be suitable for this purpose; however, the computational cost can be daunting. Here, the E(3)-equivariant neural network e3nn is used to fit the atomic polar tensor of liquid water a posteriori on top of existing molecular dynamics simulations. Notably, the introduced methodology is general and thus transferable to any other system as well. The target property is most fundamental and gives access to the IR spectrum, and more importantly, it is a highly powerful tool to directly assign IR spectral features to nuclear motion─a connection which has been pursued in the past but only using severe approximations due to the prohibitive computational cost. The herein introduced methodology overcomes this bottleneck. To benchmark the machine learning model, the IR spectrum of liquid water is calculated, indeed showing excellent agreement with the explicit reference calculation. In conclusion, the presented methodology gives a new route to calculate accurate IR spectra from molecular dynamics simulations and will facilitate the understanding of such spectra on a microscopic level.
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7
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Hu Q, Zhao H, Ouyang S, Liang Y, Yang H, Zhu X. The water structure around chloride ion investigated from D2O ↔ H2O substitution effect. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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8
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Improved Iridium/Iridium Oxide pH Electrode through Supercritical Treatment. J Electroanal Chem (Lausanne) 2022. [DOI: 10.1016/j.jelechem.2022.116740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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9
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Muñoz-Santiburcio D. Accurate diffusion coefficients of the excess proton and hydroxide in water via extensive ab initio simulations with different schemes. J Chem Phys 2022; 157:024504. [PMID: 35840376 DOI: 10.1063/5.0093958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Despite its simple molecular formula, obtaining an accurate in silico description of water is far from straightforward. Many of its very peculiar properties are quite elusive, and in particular, obtaining good estimations of the diffusion coefficients of the solvated proton and hydroxide at a reasonable computational cost has been an unsolved challenge until now. Here, I present extensive results of several unusually long ab initio molecular dynamics (MD) simulations employing different combinations of the Born-Oppenheimer and second-generation Car-Parrinello MD propagation methods with different ensembles (NVE and NVT) and thermostats, which show that these methods together with the RPBE-D3 functional provide a very accurate estimation of the diffusion coefficients of the solvated H3O+ and OH- ions, together with an extremely accurate description of several properties of neutral water (such as the structure of the liquid and its diffusion and shear viscosity coefficients). In addition, I show that the estimations of DH3O+ and DOH- depend dramatically on the simulation length, being necessary to reach timescales in the order of hundreds of picoseconds to obtain reliable results.
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Affiliation(s)
- Daniel Muñoz-Santiburcio
- CIC nanoGUNE BRTA, Tolosa Hiribidea 76, 20018 San Sebastián, Spain and Instituto de Fusión Nuclear "Guillermo Velarde," Universidad Politécnica de Madrid, C/ José Gutiérrez Abascal 2, 28006 Madrid, Spain
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10
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Schienbein P, Blumberger J. Nanosecond solvation dynamics of the hematite/liquid water interface at hybrid DFT accuracy using committee neural network potentials. Phys Chem Chem Phys 2022; 24:15365-15375. [PMID: 35703465 DOI: 10.1039/d2cp01708c] [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
Metal oxide/water interfaces play an important role in biology, catalysis, energy storage and photocatalytic water splitting. The atomistic structure at these interfaces is often difficult to characterize by experimental techniques, whilst results from ab initio molecular dynamics simulations tend to be uncertain due to the limited length and time scales accessible. In this work, we train a committee neural network potential to simulate the hematite/water interface at the hybrid DFT level of theory to reach the nanosecond timescale and systems containing more than 3000 atoms. The NNP enables us to converge dynamical properties, not possible with brute-force ab initio molecular dynamics. Our simulations uncover a rich solvation dynamics at the hematite/water interface spanning three different time scales: picosecond H-bond dynamics between surface hydroxyls and the first water layer, in-plane/out-of-plane tilt motion of surface hydroxyls on the 10 ps time scale, and diffusion of water molecules from the oxide surface characterized by a mean residence lifetime of about 60 ps. Calculation of vibrational spectra confirm that H-bonds between surface hydroxyls and first layer water molecules are stronger than H-bonds in bulk water. Our study showcases how state of the art machine learning approaches can routinely be utilized to explore the structural dynamics at transition metal oxide interfaces with complex electronic structure. It foreshadows that c-NNPs are a promising tool to tackle the sampling problem in ab initio electrochemistry with explicit solvent molecules.
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Affiliation(s)
- Philipp Schienbein
- Department of Physics and Astronomy and Thomas Young Centre, University College London, London, WC1E 6BT, UK.
| | - Jochen Blumberger
- Department of Physics and Astronomy and Thomas Young Centre, University College London, London, WC1E 6BT, UK.
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11
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Noetzel J, Schienbein P, Forbert H, Marx D. Solvation of Small Gold Clusters in Supercritical Water. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Thomsen B, Shiga M. Structures of liquid and aqueous water isotopologues at ambient temperature from ab initio path integral simulations. Phys Chem Chem Phys 2022; 24:10851-10859. [PMID: 35504275 DOI: 10.1039/d2cp00499b] [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
The heavy hydrogen isotopes D and T are found in trace amounts in water, and when their concentration increases they can play an intricate role in modulating the physical properties of the liquid. We present an analysis of the microscopic structures of ambient light water (H2O(l)), heavy water (D2O(l)), T2O(l), HDO(aq) and HTO(aq) studied by ab initio path integral molecular dynamics (PIMD). Unlike previous ab initio PIMD investigations of H2O(l) and D2O(l) [Chen et al., Phys. Rev. Lett., 2003, 91, 215503] [Machida et al., J. Chem. Phys., 2017, 148, 102324] we find that D2O(l) is more structured than H2O(l), as is predicted by the experiment. The agreement between the experiment and our simulation for H2O(l) and D2O(l) allows us to accurately predict the intra- and intermolecular structures of T2O(l) HDO(aq) and HTO(aq). T2O(l) is found to have a similar intermolecular structure to that of D2O(l), while the intramolecular structure is more compact, giving rise to a smaller dipole moment than those of H2O(l) and D2O(l). For the mixed isotope species, HDO(aq) and HTO(aq), we find smaller dipole moments and fewer hydrogen bonds when compared with the pure species H2O and D2O. We can attribute this effect to the relative compactness of the mixed isotope species, which results in a lower dipole moment than that of the pure species.
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Affiliation(s)
- Bo Thomsen
- CCSE, Japan Atomic Energy Agency, 178-4-4, Wakashiba, Kashiwa, Chiba, 277-0871, Japan.
| | - Motoyuki Shiga
- CCSE, Japan Atomic Energy Agency, 178-4-4, Wakashiba, Kashiwa, Chiba, 277-0871, Japan.
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13
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Abstract
Structures and processes at water/metal interfaces play an important technological role in electrochemical energy conversion and storage, photoconversion, sensors, and corrosion, just to name a few. However, they are also of fundamental significance as a model system for the study of solid-liquid interfaces, which requires combining concepts from the chemistry and physics of crystalline materials and liquids. Particularly interesting is the fact that the water-water and water-metal interactions are of similar strength so that the structures at water/metal interfaces result from a competition between these comparable interactions. Because water is a polar molecule and water and metal surfaces are both polarizable, explicit consideration of the electronic degrees of freedom at water/metal interfaces is mandatory. In principle, ab initio molecular dynamics simulations are thus the method of choice to model water/metal interfaces, but they are computationally still rather demanding. Here, ab initio simulations of water/metal interfaces will be reviewed, starting from static systems such as the adsorption of single water molecules, water clusters, and icelike layers, followed by the properties of liquid water layers at metal surfaces. Technical issues such as the appropriate first-principles description of the water-water and water-metal interactions will be discussed, and electrochemical aspects will be addressed. Finally, more approximate but numerically less demanding approaches to treat water at metal surfaces from first-principles will be briefly discussed.
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Affiliation(s)
- Axel Groß
- Institute of Theoretical Chemistry, Ulm University, 89069 Ulm, Germany.,Electrochemical Energy Storage, Helmholtz Institute Ulm (HIU), 89069 Ulm, Germany
| | - Sung Sakong
- Institute of Theoretical Chemistry, Ulm University, 89069 Ulm, Germany
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14
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Thomsen B, Shiga M. Ab initio study of nuclear quantum effects on sub- and supercritical water. J Chem Phys 2021; 155:194107. [PMID: 34800944 DOI: 10.1063/5.0071857] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The structures of water in the ambient, subcritical, and supercritical conditions at various densities were studied systematically by ab initio path integral molecular dynamics simulations. It was found that the nuclear quantum effects (NQEs) have a significant impact on the structure of hydrogen bonds in close contact, not only in the ambient condition but also in the sub- and supercritical conditions. The NQEs on the structure beyond the hydrogen bond contact are important in ambient water, but not much for water in the sub- and supercritical conditions. The NQEs are furthermore important for determining the number of hydrogen bonds in the ambient conditions, and this role is, however, diminished in the sub- and supercritical conditions. The NQEs do, nevertheless, show their importance in determining the intramolecular structure of water and the close contact structures of the hydrogen bonds, even at sub- and supercritical conditions. Using the RPBE-D3 functional, the computed radial distribution functions for ambient water are in excellent agreement with experimental data, upgrading our previous results using the BLYP-D2 functional [Machida et al., J. Chem. Phys. 148, 102324 (2018)]. The computed radial distribution functions for water in the sub- and supercritical conditions were carefully compared with experiment. In particular, we found that the first peak in hydrogen pair distribution functions matches only when the NQEs are taken into account.
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Affiliation(s)
- Bo Thomsen
- CCSE, Japan Atomic Energy Agency, 178-4-4, Wakashiba, Kashiwa, Chiba 277-0871, Japan
| | - Motoyuki Shiga
- CCSE, Japan Atomic Energy Agency, 178-4-4, Wakashiba, Kashiwa, Chiba 277-0871, Japan
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15
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Machine learning potentials for complex aqueous systems made simple. Proc Natl Acad Sci U S A 2021; 118:2110077118. [PMID: 34518232 PMCID: PMC8463804 DOI: 10.1073/pnas.2110077118] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2021] [Indexed: 12/23/2022] Open
Abstract
Understanding complex materials, in particular those with solid–liquid interfaces, such as water on surfaces or under confinement, is a key challenge for technological and scientific progress. Although established simulation approaches have been able to provide important atomistic insight, ab initio techniques struggle with the required time and length scales, while force field methods can often be limited in terms of their accuracy. Here we show how these limitations can be overcome in a simple and automated machine learning procedure to provide accurate models of interactions at the ab initio level, as illustrated for a variety of complex aqueous systems. These developments open up the prospect of the straightforward exploration of many technologically relevant systems by molecular simulations. Simulation techniques based on accurate and efficient representations of potential energy surfaces are urgently needed for the understanding of complex systems such as solid–liquid interfaces. Here we present a machine learning framework that enables the efficient development and validation of models for complex aqueous systems. Instead of trying to deliver a globally optimal machine learning potential, we propose to develop models applicable to specific thermodynamic state points in a simple and user-friendly process. After an initial ab initio simulation, a machine learning potential is constructed with minimum human effort through a data-driven active learning protocol. Such models can afterward be applied in exhaustive simulations to provide reliable answers for the scientific question at hand or to systematically explore the thermal performance of ab initio methods. We showcase this methodology on a diverse set of aqueous systems comprising bulk water with different ions in solution, water on a titanium dioxide surface, and water confined in nanotubes and between molybdenum disulfide sheets. Highlighting the accuracy of our approach with respect to the underlying ab initio reference, the resulting models are evaluated in detail with an automated validation protocol that includes structural and dynamical properties and the precision of the force prediction of the models. Finally, we demonstrate the capabilities of our approach for the description of water on the rutile titanium dioxide (110) surface to analyze the structure and mobility of water on this surface. Such machine learning models provide a straightforward and uncomplicated but accurate extension of simulation time and length scales for complex systems.
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16
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Liu Y, Huang K, Zhou Y, Gou D, Shi H. Hydrogen Bonding and the Structural Properties of Glycerol-Water Mixtures with a Microwave Field: a Molecular Dynamics Study. J Phys Chem B 2021; 125:8099-8106. [PMID: 34264668 DOI: 10.1021/acs.jpcb.1c03232] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In a microwave field, the dielectric properties, molecular structures, and hydrogen bonding dynamics of glycerol in its mixtures with water were determined by the molecular dynamics simulation method. The dipole-dipole correlation of glycerol is linked to the field intensity of microwaves. The results show that as the field intensity is increased, even glycerol in the second coordination shell can become correlated with each other. The structures of up to 35 glycerol molecules are observed. More than that, it was observed that lifetimes of glycerol-glycerol hydrogen bonds were prolonged, while the average hydrogen bond number was also increased. Besides, the structures in a strong microwave field mimic the weak C-H⋯O hydrogen bonds seen in high-glycerol concentration mixtures, yet the concentration is lower. These results indicate that with the assistance of the microwave field, glycerol molecules become concentrated and are more likely to establish stable interactions with others. As a consequence, the spherical clusters composed by glycerol molecules in our nanosheet synthesis experiment are easier to form.
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Affiliation(s)
- Ying Liu
- College of Electronics and Information Engineering, Sichuan University, Chengdu 610064, Sichuan, China
| | - Kama Huang
- College of Electronics and Information Engineering, Sichuan University, Chengdu 610064, Sichuan, China
| | - Yanping Zhou
- College of Electronics and Information Engineering, Sichuan University, Chengdu 610064, Sichuan, China
| | - Dezhi Gou
- College of Electronics and Information Engineering, Sichuan University, Chengdu 610064, Sichuan, China
| | - Hongxiao Shi
- College of Electronics and Information Engineering, Sichuan University, Chengdu 610064, Sichuan, China
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17
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Elbers M, Schmidt C, Sternemann C, Sahle CJ, Jahn S, Albers C, Sakrowski R, Gretarsson H, Sundermann M, Tolan M, Wilke M. Ion association in hydrothermal aqueous NaCl solutions: implications for the microscopic structure of supercritical water. Phys Chem Chem Phys 2021; 23:14845-14856. [PMID: 34223594 DOI: 10.1039/d1cp01490k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Knowledge of the microscopic structure of fluids and changes thereof with pressure and temperature is important for the understanding of chemistry and geochemical processes. In this work we investigate the influence of sodium chloride on the hydrogen-bond network in aqueous solution up to supercritical conditions. A combination of in situ X-ray Raman scattering and ab initio molecular dynamics simulations is used to probe the oxygen K-edge of the alkali halide aqueous solution in order to obtain unique information about the oxygen's local coordination around the ions, e.g. solvation-shell structure and the influence of ion pairing. The measured spectra exhibit systematic temperature dependent changes, which are entirely reproduced by calculations on the basis of structural snapshots obtained via ab initio molecular dynamics simulations. Analysis of the simulated trajectories allowed us to extract detailed structural information. This combined analysis reveals a net destabilizing effect of the dissolved ions which is reduced with rising temperature. The observed increased formation of contact ion pairs and occurrence of larger polyatomic clusters at higher temperatures can be identified as a driving force behind the increasing structural similarity between the salt solution and pure water at elevated temperatures and pressures with drawback on the role of hydrogen bonding in the hot fluid. We discuss our findings in view of recent results on hot NaOH and HCl aqueous fluids and emphasize the importance of ion pairing in the interpretation of the microscopic structure of water.
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Affiliation(s)
- Mirko Elbers
- Fakultät Physik/DELTA, Technische Universität Dortmund, D-44227 Dortmund, Germany.
| | - Christian Schmidt
- Helmholtz-Zentrum Potsdam, Deutsches GeoForschungsZentrum GFZ, Telegrafenberg, D-14473 Potsdam, Germany
| | - Christian Sternemann
- Fakultät Physik/DELTA, Technische Universität Dortmund, D-44227 Dortmund, Germany.
| | - Christoph J Sahle
- European Synchrotron Radiation Facility, F-38043 Grenoble Cedex, France
| | - Sandro Jahn
- Institut für Geologie und Mineralogie, Universität zu Köln, D-50674 Cologne, Germany
| | - Christian Albers
- Fakultät Physik/DELTA, Technische Universität Dortmund, D-44227 Dortmund, Germany.
| | - Robin Sakrowski
- Fakultät Physik/DELTA, Technische Universität Dortmund, D-44227 Dortmund, Germany.
| | - Hlynur Gretarsson
- Deutsches Elektronen-Synchrotron DESY, D-22607, Hamburg, Germany and Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Martin Sundermann
- Deutsches Elektronen-Synchrotron DESY, D-22607, Hamburg, Germany and Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Metin Tolan
- Fakultät Physik/DELTA, Technische Universität Dortmund, D-44227 Dortmund, Germany.
| | - Max Wilke
- Institut für Geowissenschaften, Universität Potsdam, D-14476 Potsdam, Germany
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18
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Maerzke KA, Yoon TJ, Jadrich RB, Leiding JA, Currier RP. First-Principles Simulations of CuCl in High-Temperature Water Vapor. J Phys Chem B 2021; 125:4794-4807. [PMID: 33938730 DOI: 10.1021/acs.jpcb.1c00083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Experimental data suggest that the solubility of copper in high-temperature water vapor is controlled by the formation of hydrated clusters of the form CuCl(H2O)n, where the average number of water molecules in the cluster generally increases with increasing density [Migdisov, A. A.; et al. Geochim. Cosmochim. Acta 2014, 129, 33-53]. However, the precise nature of these clusters is difficult to probe experimentally. Moreover, there are some discrepancies between experimental estimates of average cluster size and prior simulation work [Mei, Y. Geofluids 2018, 2018, 4279124]. We have performed first-principles Monte Carlo (MC) and molecular dynamics (MD) simulations to explore these clusters in finer detail. We find that molecular dynamics is not the most appropriate technique for studying aggregation in vapor phases, even at relatively high temperatures. Specifically, our MD simulations exhibit substantial problems in adequately sampling the equilibrium cluster size distribution. In contrast, MC simulations with specialized cluster moves are able to accurately sample the phase space of hydrogen-bonding vapors. At all densities, we find a stable, slightly distorted linear H2O-Cu-Cl structure, which is in agreement with the earlier simulations, surrounded by a variable number of water molecules. The surrounding water molecules do not form a well-defined second solvation shell but rather a loose network of hydrogen-bonded water with molecular CuCl on the outside edge of the water cluster. We also find a broad distribution of hydration numbers, especially at higher densities. In contrast to previous simulation work but in agreement with experimental data, we find that the average hydration number substantially increases with increasing density. Moreover, the value of the hydration number depends on the choice of cluster definition.
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Affiliation(s)
- Katie A Maerzke
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Tae Jun Yoon
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Ryan B Jadrich
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.,Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Jeffery A Leiding
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Robert P Currier
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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