1
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Zhang Q, Wang RS, Wang L. Neural canonical transformations for vibrational spectra of molecules. J Chem Phys 2024; 161:024103. [PMID: 38979703 DOI: 10.1063/5.0209255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 06/19/2024] [Indexed: 07/10/2024] Open
Abstract
The behavior of polyatomic molecules around their equilibrium positions can be regarded as that of quantum-coupled anharmonic oscillators. Solving the corresponding Schrödinger equations enables the interpretation or prediction of the experimental spectra of molecules. In this study, we developed a novel approach for solving the excited states of anharmonic vibrational systems. The normal coordinates of the molecules are transformed into new coordinates through a normalizing flow parameterized by a neural network. This facilitates the construction of a set of orthogonal many-body variational wavefunctions. This methodology has been validated on an exactly solvable 64-dimensional coupled harmonic oscillator, yielding numerical results with a relative error of 10-6. The neural canonical transformations are also applied to calculate the energy levels of two specific molecules, acetonitrile (CH3CN) and ethylene oxide (C2H4O). These molecules involve 12 and 15 vibrational modes, respectively. A key advantage of this approach is its flexibility concerning the potential energy surface, as it requires no specific form. Furthermore, this method can be readily implemented on large-scale distributed computing platforms, making it easy to extend to investigating complex vibrational structures.
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Affiliation(s)
- Qi Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Rui-Si Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
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2
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He XL, Zhao W, Xie Y, Hermann A, Hemley RJ, Liu H, Ma Y. Predicted hot superconductivity in LaSc 2H 24 under pressure. Proc Natl Acad Sci U S A 2024; 121:e2401840121. [PMID: 38900793 PMCID: PMC11214075 DOI: 10.1073/pnas.2401840121] [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: 01/27/2024] [Accepted: 05/23/2024] [Indexed: 06/22/2024] Open
Abstract
The recent theory-driven discovery of a class of clathrate hydrides (e.g., CaH6, YH6, YH9, and LaH10) with superconducting critical temperatures (Tc) well above 200 K has opened the prospects for "hot" superconductivity above room temperature under pressure. Recent efforts focus on the search for superconductors among ternary hydrides that accommodate more diverse material types and configurations compared to binary hydrides. Through extensive computational searches, we report the prediction of a unique class of thermodynamically stable clathrate hydrides structures consisting of two previously unreported H24 and H30 hydrogen clathrate cages at megabar pressures. Among these phases, LaSc2H24 shows potential hot superconductivity at the thermodynamically stable pressure range of 167 to 300 GPa, with calculated Tcs up to 331 K at 250 GPa and 316 K at 167 GPa when the important effects of anharmonicity are included. The very high critical temperatures are attributed to an unusually large hydrogen-derived density of states at the Fermi level arising from the newly reported peculiar H30 as well as H24 cages in the structure. Our predicted introduction of Sc in the La-H system is expected to facilitate future design and realization of hot superconductors in ternary clathrate superhydrides.
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Affiliation(s)
- Xin-Ling He
- Key Laboratory of Material Simulation Methods and Software of Ministry of Education, College of Physics, Jilin University, Changchun130012, China
- Institute of Physics, Henan Academy of Sciences, Zhengzhou450046, China
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun130012, China
| | - Wenbo Zhao
- Key Laboratory of Material Simulation Methods and Software of Ministry of Education, College of Physics, Jilin University, Changchun130012, China
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun130012, China
| | - Yu Xie
- Key Laboratory of Material Simulation Methods and Software of Ministry of Education, College of Physics, Jilin University, Changchun130012, China
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun130012, China
| | - Andreas Hermann
- Centre for Science at Extreme Conditions and Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Edinburgh, EdinburghEH9 3FD, United Kingdom
| | - Russell J. Hemley
- Department of Physics, University of Illinois Chicago, Chicago, IL60607
- Department of Chemistry, University of Illinois Chicago, Chicago, IL60607
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL60607
| | - Hanyu Liu
- Key Laboratory of Material Simulation Methods and Software of Ministry of Education, College of Physics, Jilin University, Changchun130012, China
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun130012, China
- International Center of Future Science, Jilin University, Changchun130012, China
| | - Yanming Ma
- Key Laboratory of Material Simulation Methods and Software of Ministry of Education, College of Physics, Jilin University, Changchun130012, China
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun130012, China
- International Center of Future Science, Jilin University, Changchun130012, China
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3
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Furci M, Marini G, Calandra M. First-Order Rhombohedral-to-Cubic Phase Transition in Photoexcited GeTe. PHYSICAL REVIEW LETTERS 2024; 132:236101. [PMID: 38905679 DOI: 10.1103/physrevlett.132.236101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 04/23/2024] [Indexed: 06/23/2024]
Abstract
Photoexcited GeTe undergoes a nonthermal phase transition from a rhombohedral to a rocksalt crystalline phase. The microscopic mechanism and the nature of the transition are unclear. By using constrained density functional perturbation theory and by accounting for quantum anharmonicity within the stochastic self-consistent harmonic approximation, we show that the nonthermal phase transition is strongly first order and does not involve phonon softening, at odds with the thermal one. The transition is driven by the closure of the single particle gap in the photoexcited rhombohedral phase. Finally, we show that ultrafast x-ray diffraction data are consistent with a coexistence of the two phases, as expected in a first order transition. Our results are relevant for the understanding of phase transitions and bonding in phase change materials.
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Affiliation(s)
- Matteo Furci
- Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo, Italy
| | - Giovanni Marini
- Graphene Labs, Fondazione Istituto Italiano di Tecnologia, Via Morego, I-16163 Genova, Italy
| | - Matteo Calandra
- Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo, Italy
- Graphene Labs, Fondazione Istituto Italiano di Tecnologia, Via Morego, I-16163 Genova, Italy
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252 Paris, France
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4
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Dolui K, Conway LJ, Heil C, Strobel TA, Prasankumar RP, Pickard CJ. Feasible Route to High-Temperature Ambient-Pressure Hydride Superconductivity. PHYSICAL REVIEW LETTERS 2024; 132:166001. [PMID: 38701475 DOI: 10.1103/physrevlett.132.166001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 03/01/2024] [Indexed: 05/05/2024]
Abstract
A key challenge in materials discovery is to find high-temperature superconductors. Hydrogen and hydride materials have long been considered promising materials displaying conventional phonon-mediated superconductivity. However, the high pressures required to stabilize these materials have restricted their application. Here, we present results from high-throughput computation, considering a wide range of high-symmetry ternary hydrides from across the periodic table at ambient pressure. This large composition space is then reduced by considering thermodynamic, dynamic, and magnetic stability before direct estimations of the superconducting critical temperature. This approach has revealed a metastable ambient-pressure hydride superconductor, Mg_{2}IrH_{6}, with a predicted critical temperature of 160 K, comparable to the highest temperature superconducting cuprates. We propose a synthesis route via a structurally related insulator, Mg_{2}IrH_{7}, which is thermodynamically stable above 15 GPa, and discuss the potential challenges in doing so.
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Affiliation(s)
- Kapildeb Dolui
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB30FS, United Kingdom
| | - Lewis J Conway
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB30FS, United Kingdom
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Christoph Heil
- Institute of Theoretical and Computational Physics, Graz University of Technology, NAWI Graz, 8010 Graz, Austria
| | - Timothy A Strobel
- Earth and Planets Laboratory, Carnegie Institution for Science, 5241 Broad Branch Road, Northwest, Washington, DC 20015, USA
| | | | - Chris J Pickard
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB30FS, United Kingdom
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
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5
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Peng B, Lange GF, Bennett D, Wang K, Slager RJ, Monserrat B. Photoinduced Electronic and Spin Topological Phase Transitions in Monolayer Bismuth. PHYSICAL REVIEW LETTERS 2024; 132:116601. [PMID: 38563950 DOI: 10.1103/physrevlett.132.116601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 02/09/2024] [Indexed: 04/04/2024]
Abstract
Ultrathin bismuth exhibits rich physics including strong spin-orbit coupling, ferroelectricity, nontrivial topology, and light-induced structural dynamics. We use ab initio calculations to show that light can induce structural transitions to four transient phases in bismuth monolayers. These light-induced phases exhibit nontrivial topological character, which we illustrate using the recently introduced concept of spin bands and spin-resolved Wilson loops. Specifically, we find that the topology changes via the closing of the electron and spin band gaps during photoinduced structural phase transitions, leading to distinct edge states. Our study provides strategies to tailor electronic and spin topology via ultrafast control of photoexcited carriers and associated structural dynamics.
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Affiliation(s)
- Bo Peng
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Gunnar F Lange
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Daniel Bennett
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Kang Wang
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Robert-Jan Slager
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Bartomeu Monserrat
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
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6
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Kim DS, Xu M, LeBeau JM. Modeling Temperature-Dependent Electron Thermal Diffuse Scattering via Machine-Learned Interatomic Potentials and Path-Integral Molecular Dynamics. PHYSICAL REVIEW LETTERS 2024; 132:086301. [PMID: 38457736 DOI: 10.1103/physrevlett.132.086301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 01/12/2024] [Accepted: 01/25/2024] [Indexed: 03/10/2024]
Abstract
Electron thermal diffuse scattering is shown to be sensitive to subtle changes in atomic vibrations and shows promise in assessing lattice dynamics at nanometer resolution. Here, we demonstrate that machine-learned interatomic potentials (MLIPs) and path-integral molecular dynamics can accurately capture the potential energy landscape and lattice dynamics needed to describe electron thermal diffuse scattering. Using SrTiO_{3} as a test bed at cryogenic and room temperatures, we compare electron thermal diffuse scattering simulations using different approximations to incorporate thermal motion. Only when the simulations are based on quantum mechanically accurate MLIPs in combination with path-integral molecular dynamics that include nuclear quantum effects is there excellent agreement with experiments.
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Affiliation(s)
- Dennis S Kim
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Michael Xu
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - James M LeBeau
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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7
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Lucrezi R, Ferreira PP, Aichhorn M, Heil C. Temperature and quantum anharmonic lattice effects on stability and superconductivity in lutetium trihydride. Nat Commun 2024; 15:441. [PMID: 38199988 PMCID: PMC10781996 DOI: 10.1038/s41467-023-44326-4] [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: 06/13/2023] [Accepted: 12/08/2023] [Indexed: 01/12/2024] Open
Abstract
In this work, we resolve conflicting experimental and theoretical findings related to the dynamical stability and superconducting properties of [Formula: see text]-LuH3, which was recently suggested as the parent phase harboring room-temperature superconductivity at near-ambient pressures. Including temperature and quantum anharmonic lattice effects in our calculations, we demonstrate that the theoretically predicted structural instability of the [Formula: see text] phase near ambient pressures is suppressed for temperatures above 200 K. We provide a p-T phase diagram for stability up to pressures of 6 GPa, where the required temperature for stability is reduced to T > 80 K. We also determine the superconducting critical temperature Tc of [Formula: see text]-LuH3 within the Migdal-Eliashberg formalism, using temperature- and quantum-anharmonically-corrected phonon dispersions, finding that the expected Tc for electron-phonon mediated superconductivity is in the range of 50-60 K, i.e., well below the temperatures required to stabilize the lattice. When considering moderate doping based on rigidly shifting the Fermi level, Tc decreases for both hole and electron doping. Our results thus provide evidence that any observed room-temperature superconductivity in pure or doped [Formula: see text]-LuH3, if confirmed, cannot be explained by a conventional electron-phonon mediated pairing mechanism.
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Affiliation(s)
- Roman Lucrezi
- Institute of Theoretical and Computational Physics, Graz University of Technology, NAWI Graz, 8010 Graz, Austria
| | - Pedro P Ferreira
- Institute of Theoretical and Computational Physics, Graz University of Technology, NAWI Graz, 8010 Graz, Austria
- Universidade de São Paulo, Escola de Engenharia de Lorena, DEMAR, 12612-550, Lorena, Brazil
| | - Markus Aichhorn
- Institute of Theoretical and Computational Physics, Graz University of Technology, NAWI Graz, 8010 Graz, Austria
| | - Christoph Heil
- Institute of Theoretical and Computational Physics, Graz University of Technology, NAWI Graz, 8010 Graz, Austria.
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8
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Jaykhedkar N, Bystrický R, Sýkora M, Bučko T. Investigating the role of dispersion corrections and anharmonic effects on the phase transition in SrZrS3: A systematic analysis from AIMD free energy calculations. J Chem Phys 2024; 160:014710. [PMID: 38180257 DOI: 10.1063/5.0185319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 12/13/2023] [Indexed: 01/06/2024] Open
Abstract
A thermally driven needle-like (NL) to distorted perovskite (DP) phase transition in SrZrS3 was investigated by means of ab initio free energy calculations accelerated by machine learning. As a first step, a systematic screening of the methods to include long-range interactions in semilocal density functional theory Perdew-Burke-Ernzerhof calculations was performed. Out of the ten correction schemes tested, the Tkatchenko-Scheffler method with iterative Hirshfeld partitioning method was found to yield the best match between calculated and experimental lattice geometries, while predicting the correct order of stability of NL and DP phases at zero temperature. This method was then used in free energy calculations, performed using several approaches, so as to determine the effect of various anharmonicity contributions, such as the anisotropic thermal lattice expansion or the thermally induced internal structure changes, on the phase transition temperature (TNP→DP). Accounting for the full anharmonicity by combining the NPT molecular dynamics data with thermodynamic integration with harmonic reference provided our best estimate of TNL→DP = 867 K. Although this result is ∼150 K lower than the experimental value, it still provides an improvement by nearly 300 K compared to the previous theoretical report by Koocher et al. [Inorg. Chem. 62, 11134-11141 (2023)].
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Affiliation(s)
- Namrata Jaykhedkar
- Laboratory of Advanced Materials, Comenius University, Ilkovičova 6, 84104 Bratislava, Slovakia
| | - Roman Bystrický
- Laboratory of Advanced Materials, Comenius University, Ilkovičova 6, 84104 Bratislava, Slovakia
- Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská Cesta 9, 84236 Bratislava, Slovakia
| | - Milan Sýkora
- Laboratory of Advanced Materials, Comenius University, Ilkovičova 6, 84104 Bratislava, Slovakia
| | - Tomáš Bučko
- Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská Cesta 9, 84236 Bratislava, Slovakia
- Department of Physical and Theoretical Chemistry, Comenius University, Ilkovičova 6, 84104 Bratislava, Slovakia
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9
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Drużbicki K, Gila-Herranz P, Marin-Villa P, Gaboardi M, Armstrong J, Fernandez-Alonso F. Cation Dynamics as Structure Explorer in Hybrid Perovskites-The Case of MAPbI 3. CRYSTAL GROWTH & DESIGN 2024; 24:391-404. [PMID: 38188269 PMCID: PMC10768891 DOI: 10.1021/acs.cgd.3c01112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/20/2023] [Accepted: 12/01/2023] [Indexed: 01/09/2024]
Abstract
Hybrid organic-inorganic perovskites exhibit remarkable potential as cost-effective and high-efficiency materials for photovoltaic applications. Their exceptional chemical tunability opens further routes for optimizing their optical and electronic properties through structural engineering. Nevertheless, the extraordinary softness of the lattice, stemming from its interconnected organic-inorganic composition, unveils formidable challenges in structural characterization. Here, by focusing on the quintessential methylammonium lead triiodide, MAPbI3, we combine first-principles modeling with high-resolution neutron scattering data to identify the key stationary points on its shallow potential energy landscape. This combined experimental and computational approach enables us to benchmark the performance of a collection of semilocal exchange-correlation functionals and to track the local distortions of the perovskite framework, hallmarked by the inelastic neutron scattering response of the organic cation. By conducting a thorough examination of structural distortions, we introduce the IKUR-PVP-1 structural data set. This data set contains nine mechanically stable structural models, each manifesting a distinct vibrational response. IKUR-PVP-1 constitutes a valuable resource for assessing thermal behavior in the low-temperature perovskite phase. In addition, it paves the way for the development of accurate force fields, enabling a comprehensive understanding of the interplay between the structure and dynamics in MAPbI3 and related hybrid perovskites.
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Affiliation(s)
- Kacper Drużbicki
- Materials
Physics Center, CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian 20018, Spain
- Polish
Academy of Sciences, Centre of Molecular and Macromolecular Studies, Sienkiewicza 112, Lodz 90-363, Poland
| | - Pablo Gila-Herranz
- Materials
Physics Center, CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian 20018, Spain
| | - Pelayo Marin-Villa
- Materials
Physics Center, CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian 20018, Spain
| | - Mattia Gaboardi
- Materials
Physics Center, CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian 20018, Spain
- C.S.G.I.
& Chemistry Department, University of
Pavia, Viale Taramelli,
16, Pavia 27100, Italy
| | - Jeff Armstrong
- ISIS
Neutron and Muon Facility, Rutherford Appleton
Laboratory, Didcot OX11 0QX, U.K.
| | - Felix Fernandez-Alonso
- Materials
Physics Center, CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, Donostia-San Sebastian 20018, Spain
- Donostia
International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, Donostia-San
Sebastian 20018, Spain
- IKERBASQUE,
Basque Foundation for Science, Plaza Euskadi 5, Bilbao 48009, Spain
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10
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Cerqueira TFT, Sanna A, Marques MAL. Sampling the Materials Space for Conventional Superconducting Compounds. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2307085. [PMID: 37985412 DOI: 10.1002/adma.202307085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 11/03/2023] [Indexed: 11/22/2023]
Abstract
A large scale study of conventional superconducting materials using a machine-learning accelerated high-throughput workflow is performed, starting by creating a comprehensive dataset of around 7000 electron-phonon calculations performed with reasonable convergence parameters. This dataset is then used to train a robust machine learning model capable of predicting the electron-phonon and superconducting properties based on structural, compositional, and electronic ground-state properties. Using this machine, the transition temperatures (Tc ) of approximately 200 000 metallic compounds are evaluated, all of which are on the convex hull of thermodynamic stability (or close to it) to maximize the probability of synthesizability. Compounds predicted to have Tc values exceeding 5 K are further validated using density-functional perturbation theory. As a result, 541 compounds with Tc values surpassing 10 K, encompassing a variety of crystal structures and chemical compositions, are identified. This work is complemented with a detailed examination of several interesting materials, including nitrides, hydrides, and intermetallic compounds. Particularly noteworthy is LiMoN2 , which is predicted to be superconducting in the stoichiometric trigonal phase, with a Tc exceeding 38 K. LiMoN2 has previously been synthesized in this phase, further heightening its potential for practical applications.
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Affiliation(s)
- Tiago F T Cerqueira
- CFisUC, Department of Physics, University of Coimbra, Rua Larga, Coimbra, 3004-516, Portugal
| | - Antonio Sanna
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120, Halle, Germany
| | - Miguel A L Marques
- Research Center Future Energy Materials and Systems of the University Alliance Ruhr, Faculty of Mechanical Engineering, Ruhr University Bochum, Universitätsstraße 150, D-44801, Bochum, Germany
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11
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Ranieri U, Di Cataldo S, Rescigno M, Monacelli L, Gaal R, Santoro M, Andriambariarijaona L, Parisiades P, De Michele C, Bove LE. Observation of the most H 2-dense filled ice under high pressure. Proc Natl Acad Sci U S A 2023; 120:e2312665120. [PMID: 38109537 PMCID: PMC10756306 DOI: 10.1073/pnas.2312665120] [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: 07/26/2023] [Accepted: 10/30/2023] [Indexed: 12/20/2023] Open
Abstract
Hydrogen hydrates are among the basic constituents of our solar system's outer planets, some of their moons, as well Neptune-like exo-planets. The details of their high-pressure phases and their thermodynamic conditions of formation and stability are fundamental information for establishing the presence of hydrogen hydrates in the interior of those celestial bodies, for example, against the presence of the pure components (water ice and molecular hydrogen). Here, we report a synthesis path and experimental observation, by X-ray diffraction and Raman spectroscopy measurements, of the most H[Formula: see text]-dense phase of hydrogen hydrate so far reported, namely the compound 3 (or C[Formula: see text]). The detailed characterisation of this hydrogen-filled ice, based on the crystal structure of cubic ice I (ice I[Formula: see text]), is performed by comparing the experimental observations with first-principles calculations based on density functional theory and the stochastic self-consistent harmonic approximation. We observe that the extreme (up to 90 GPa and likely beyond) pressure stability of this hydrate phase is due to the close-packed geometry of the hydrogen molecules caged in the ice I[Formula: see text] skeleton.
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Affiliation(s)
- Umbertoluca Ranieri
- Dipartimento di Fisica, Sapienza Università di Roma, 00185Roma, Italy
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, EH9 3FDEdinburgh, United Kingdom
| | - Simone Di Cataldo
- Dipartimento di Fisica, Sapienza Università di Roma, 00185Roma, Italy
- Institut für Festkörperphysik, Technische Universität Wien, 1040Wien, Austria
| | - Maria Rescigno
- Dipartimento di Fisica, Sapienza Università di Roma, 00185Roma, Italy
- Laboratory of Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015Lausanne, Switzerland
| | - Lorenzo Monacelli
- Theory and Simulation of Materials, and National Centre for Computational Design and Discovery of Novel Materials, École Polytechnique Fédérale de Lausanne, 1015Lausanne, Switzerland
| | - Richard Gaal
- Laboratory of Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015Lausanne, Switzerland
| | - Mario Santoro
- Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica, CNR-INO, Sesto Fiorentino, 50019, Italy
- European Laboratory for Nonlinear Spectroscopy, LENS, Sesto Fiorentino (FI), 50019, Italy
| | - Leon Andriambariarijaona
- Sorbonne Université, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, 75252Paris, France
| | - Paraskevas Parisiades
- Sorbonne Université, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, 75252Paris, France
| | | | - Livia Eleonora Bove
- Dipartimento di Fisica, Sapienza Università di Roma, 00185Roma, Italy
- Laboratory of Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015Lausanne, Switzerland
- Sorbonne Université, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, 75252Paris, France
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12
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Mocatti S, Marini G, Calandra M. Light-Induced Nonthermal Phase Transition to the Topological Crystalline Insulator State in SnSe. J Phys Chem Lett 2023; 14:9329-9334. [PMID: 37819838 PMCID: PMC10591509 DOI: 10.1021/acs.jpclett.3c02450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 10/05/2023] [Indexed: 10/13/2023]
Abstract
Femtosecond pulses have been used to reveal hidden broken symmetry states and induce transitions to metastable states. However, these states are mostly transient and disappear after laser removal. Photoinduced phase transitions toward crystalline metastable states with a change of topological order are rare and difficult to predict and realize experimentally. Here, by using constrained density functional perturbation theory and accounting for light-induced quantum anharmonicity, we show that ultrafast lasers can permanently transform the topologically trivial orthorhombic structure of SnSe into the topological crystalline insulating rocksalt phase via a first-order nonthermal phase transition. We describe the reaction path and evaluate the critical fluence and possible decay channels after photoexcitation. Our simulations of the photoexcited structural and vibrational properties are in excellent agreement with recent pump-probe data in the intermediate fluence regime below the transition with an error on the curvature of the quantum free energy of the photoexcited state that is smaller than 2%.
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Affiliation(s)
- Stefano Mocatti
- Department of Physics, University
of Trento, Via Sommarive 14, 38123 Povo, Italy
| | - Giovanni Marini
- Department of Physics, University
of Trento, Via Sommarive 14, 38123 Povo, Italy
| | - Matteo Calandra
- Department of Physics, University
of Trento, Via Sommarive 14, 38123 Povo, Italy
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13
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Mosquera-Lois I, Kavanagh SR, Klarbring J, Tolborg K, Walsh A. Imperfections are not 0 K: free energy of point defects in crystals. Chem Soc Rev 2023; 52:5812-5826. [PMID: 37565783 DOI: 10.1039/d3cs00432e] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Defects determine many important properties and applications of materials, ranging from doping in semiconductors, to conductivity in mixed ionic-electronic conductors used in batteries, to active sites in catalysts. The theoretical description of defect formation in crystals has evolved substantially over the past century. Advances in supercomputing hardware, and the integration of new computational techniques such as machine learning, provide an opportunity to model longer length and time-scales than previously possible. In this Tutorial Review, we cover the description of free energies for defect formation at finite temperatures, including configurational (structural, electronic, spin) and vibrational terms. We discuss challenges in accounting for metastable defect configurations, progress such as machine learning force fields and thermodynamic integration to directly access entropic contributions, and bottlenecks in going beyond the dilute limit of defect formation. Such developments are necessary to support a new era of accurate defect predictions in computational materials chemistry.
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Affiliation(s)
- Irea Mosquera-Lois
- Thomas Young Centre & Department of Materials, Imperial College London, London SW7 2AZ, UK.
| | - Seán R Kavanagh
- Thomas Young Centre & Department of Materials, Imperial College London, London SW7 2AZ, UK.
- Thomas Young Centre & Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK
| | - Johan Klarbring
- Thomas Young Centre & Department of Materials, Imperial College London, London SW7 2AZ, UK.
- Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83, Linköping, Sweden
| | - Kasper Tolborg
- Thomas Young Centre & Department of Materials, Imperial College London, London SW7 2AZ, UK.
- I-X, Imperial College London, London W12 0BZ, UK
| | - Aron Walsh
- Thomas Young Centre & Department of Materials, Imperial College London, London SW7 2AZ, UK.
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
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14
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Tolborg K, Walsh A. Exploring the High-Temperature Stabilization of Cubic Zirconia from Anharmonic Lattice Dynamics. CRYSTAL GROWTH & DESIGN 2023; 23:3314-3319. [PMID: 37159659 PMCID: PMC10161191 DOI: 10.1021/acs.cgd.2c01458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 03/30/2023] [Indexed: 05/11/2023]
Abstract
Finite-temperature stability of crystals is of continuous relevance in solid-state chemistry with many important properties only emerging in high-temperature polymorphs. Currently, the discovery of new phases is largely serendipitous due to a lack of computational methods to predict crystal stability with temperature. Conventional methods use harmonic phonon theory, but this breaks down when imaginary phonon modes are present. Anharmonic phonon methods are required to describe dynamically stabilized phases. We investigate the high-temperature tetragonal-to-cubic phase transition of ZrO2 based on first-principles anharmonic lattice dynamics and molecular dynamics simulations as an archetypical example of a phase transition involving a soft phonon mode. Anharmonic lattice dynamics calculations and free energy analysis suggest that the stability of cubic zirconia cannot be attributed solely to anharmonic stabilization and is thus absent for the pristine crystal. Instead, an additional entropic stabilization is suggested to arise from spontaneous defect formation, which is also responsible for superionic conductivity at elevated temperatures.
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Affiliation(s)
- Kasper Tolborg
- Department
of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Aron Walsh
- Department
of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
- Department
of Physics, Ewha Womans University, Seoul 03760, Korea
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15
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Amsler J, Plessow PN, Studt F, Bučko T. Anharmonic Correction to Free Energy Barriers from DFT-Based Molecular Dynamics Using Constrained Thermodynamic Integration. J Chem Theory Comput 2023; 19:2455-2468. [PMID: 37043693 DOI: 10.1021/acs.jctc.3c00169] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
For the calculation of anharmonic contributions to free energy barriers, constrained thermodynamic λ-path integration (λ-TI) from a harmonic reference force field to density functional theory is presented as an alternative to the established Blue Moon ensemble method (ξ-TI), in which free energy gradients along the reaction coordinate ξ are integrated. With good agreement in all cases, the λ-TI method is benchmarked against the ξ-TI method for several reactions, including the internal CH3 group rotation in ethane, a nucleophilic substitution of CH3Cl, a retro-Diels-Alder reaction, and a proton transfer in zeolite H-SSZ-13. An advantage of λ-TI is that one can use virtually any reference state to compute anharmonic contributions to reaction free energies or free energy barriers. This is particularly relevant for catalysis, where it is now possible to compute anharmonic corrections to the free energy of a transition state relative to any reference, for example, the most stable state of the active site and the reactants in the gas phase. This is in contrast to ξ-TI, where free energy barriers can only be computed relative to an initial state with all reactants coadsorbed. Finally, the Bennett acceptance ratio method combined with λ-TI is demonstrated to reduce the number of required integration grid points with tolerable accuracy, favoring thus λ-TI over ξ-TI in terms of computational efficiency.
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Affiliation(s)
- Jonas Amsler
- Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Philipp N Plessow
- Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Felix Studt
- Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Kaiserstr. 12, 76131 Karlsruhe, Germany
| | - Tomáš Bučko
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, SK-84215 Bratislava, Slovakia
- Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84236 Bratislava, Slovakia
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16
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Fumega AO, Diego J, Pardo V, Blanco-Canosa S, Errea I. Anharmonicity Reveals the Tunability of the Charge Density Wave Orders in Monolayer VSe 2. NANO LETTERS 2023; 23:1794-1800. [PMID: 36825982 PMCID: PMC9999451 DOI: 10.1021/acs.nanolett.2c04584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 02/22/2023] [Indexed: 06/18/2023]
Abstract
VSe2 is a layered compound that has attracted great attention due to its proximity to a ferromagnetic state that is quenched by its charge density wave (CDW) phase. In the monolayer limit, unrelated experiments have reported different CDW orders with different transition temperatures, making this monolayer very controversial. Here we perform first-principles nonperturbative anharmonic phonon calculations in monolayer VSe2 in order to estimate the CDW order and the corresponding transition temperature. They reveal that monolayer VSe2 develops two independent charge density wave orders that compete as a function of strain. Variations of only 1.5% in the lattice parameter are enough to stabilize one order or the other. Moreover, we analyze the impact of external Lennard-Jones interactions, showing that these can act together with anharmonicity to suppress the CDW orders. Our results solve previous experimental contradictions, highlighting the high tunability and substrate dependency of the CDW orders of monolayer VSe2.
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Affiliation(s)
| | - Josu Diego
- Fisika
Aplikatua Saila, Gipuzkoako Ingeniaritza Eskola, University of the Basque Country (UPV/EHU), 20018 San Sebastián, Spain
- Centro
de Física de Materiales (CSIC-UPV/EHU), 20018 San Sebastián, Spain
| | - Victor Pardo
- Departamento
de Física Aplicada, Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Spain
- Instituto
de Materiais iMATUS, Universidade de Santiago
de Compostela, 15782 Santiago de Compostela, Spain
| | - Santiago Blanco-Canosa
- Donostia
International Physics Center (DIPC), 20018 San Sebastián, Spain
- IKERBASQUE, Basque Foundation
for Science, 48013 Bilbao, Spain
| | - Ion Errea
- Fisika
Aplikatua Saila, Gipuzkoako Ingeniaritza Eskola, University of the Basque Country (UPV/EHU), 20018 San Sebastián, Spain
- Centro
de Física de Materiales (CSIC-UPV/EHU), 20018 San Sebastián, Spain
- Donostia
International Physics Center (DIPC), 20018 San Sebastián, Spain
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17
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Monacelli L, Marzari N. First-Principles Thermodynamics of CsSnI 3. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2023; 35:1702-1709. [PMID: 36873625 PMCID: PMC9979598 DOI: 10.1021/acs.chemmater.2c03475] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/25/2023] [Indexed: 06/18/2023]
Abstract
CsSnI3 is a promising ecofriendly solution for energy harvesting technologies. It exists at room temperature in either a black perovskite polymorph or a yellow 1D double-chain, which irreversibly deteriorates in the air. In this work, we unveil the relative thermodynamic stability between the two structures with a first-principles sampling of the CsSnI3 finite-temperature phase diagram, discovering how it is driven by anomalously large quantum and anharmonic ionic fluctuations. Thanks to a comprehensive treatment of anharmonicity, the simulations deliver a remarkable agreement with known experimental data for the transition temperatures of the orthorhombic, rhombohedral, and cubic perovskite structures and the thermal expansion coefficient. We disclose how the perovskite polymorphs are the ground state above 270 K and discover an abnormal decrease in heat capacity upon heating in the cubic black perovskite. Our results also significantly downplay the Cs+ rattling modes' contribution to mechanical instability. The remarkable agreement with experiments validates our methodology, which can be systematically applied to all metal halides.
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18
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Finkler JA, Goedecker S. Experimental absence of the non-perovskite ground state phases of MaPbI 3 explained by a Funnel Hopping Monte Carlo study based on a neural network potential. MATERIALS ADVANCES 2023; 4:184-194. [PMID: 36685989 PMCID: PMC9812259 DOI: 10.1039/d2ma00958g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 11/11/2022] [Indexed: 06/17/2023]
Abstract
Methylammonium lead iodide is a material known for its exceptional opto-electronic properties that make it a promising candidate for many high performance applications, such as light emitting diodes or solar cells. A recent computational structure search revealed two previously unknown non-perovskite polymorphs, that are lower in energy than the experimentally observed perovskite phases. To investigate the elusiveness of the non-perovskite phases in experimental studies, we extended our Funnel Hopping Monte Carlo (FHMC) method to periodic systems and performed extensive MC simulations driven by a machine learned potential. FHMC simulations that also include these newly discovered non-perovskite phases show that above temperatures of 200 K the perovskite phases are thermodynamically preferred. A comparison with the quasi-harmonic approximation highlights the importance of anharmonic effects captured by FHMC.
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Affiliation(s)
- Jonas A Finkler
- Department of Physics, University of Basel Klingelbergstrasse 82 4056 Basel Switzerland
| | - Stefan Goedecker
- Department of Physics, University of Basel Klingelbergstrasse 82 4056 Basel Switzerland
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19
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Togo A, Hayashi H, Tadano T, Tsutsui S, Tanaka I. LO-mode phonon of KCl and NaCl at 300 K by inelastic x-ray scattering measurements and first principles calculations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:365401. [PMID: 35728792 DOI: 10.1088/1361-648x/ac7b01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 06/21/2022] [Indexed: 06/15/2023]
Abstract
Longitudinal-optical (LO) mode phonon branches of KCl and NaCl were measured using inelastic x-ray scattering (IXS) at 300 K and calculated by the first-principles phonon calculation with the stochastic self-consistent harmonic approximation. Spectral shapes of the IXS measurements and calculated spectral functions agreed well. We analyzed the calculated spectral functions that provide higher resolutions of the spectra than the IXS measurements. Due to strong anharmonicity, the spectral functions of these phonon branches have several peaks and the LO modes along Γ-L paths are disconnected.
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Affiliation(s)
- Atsushi Togo
- Research and Services Division of Materials Data and Integrated System, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
- Center for Elements Strategy Initiative for Structural Materials, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Hiroyuki Hayashi
- Department of Materials Science and Engineering, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Terumasa Tadano
- Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
| | - Satoshi Tsutsui
- Japan Synchrotron Radiation Research Institute, Sayo-cho, Hyogo 679-5198, Japan
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511, Japan
| | - Isao Tanaka
- Center for Elements Strategy Initiative for Structural Materials, Kyoto University, Sakyo, Kyoto 606-8501, Japan
- Department of Materials Science and Engineering, Kyoto University, Sakyo, Kyoto 606-8501, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Atsuta, Nagoya 456-8587, Japan
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20
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Errea I. Superconducting hydrides on a quantum landscape. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:231501. [PMID: 35255480 DOI: 10.1088/1361-648x/ac5b46] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 03/07/2022] [Indexed: 06/14/2023]
Abstract
Reaching superconductivity at ambient conditions is one of the biggest scientific dreams. The discoveries in the last few years at high pressures place hydrogen-based compounds as the best candidates for making it true. As the recent history shows, first-principles calculations are expected to continue guiding the experimental quest in the right track in the coming years. Considering that ionic quantum fluctuations largely affect the crystal structure and the vibrational properties of superconducting hydrides, in many cases making them thermodynamically stable at much lower pressures than expected, it will be crucial to include such effects on the futureab initiopredictions. The prospects for low-pressure high critical-temperature compounds are wide open, even at ambient pressure.
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Affiliation(s)
- Ion Errea
- Fisika Aplikatua Saila, Gipuzkoako Ingeniaritza Eskola, University of the Basque Country (UPV/EHU), Europa Plaza 1, 20018 Donostia/San Sebastián, Spain
- Centro de Física de Materiales (CSIC-UPV/EHU), Manuel de Lardizabal pasealekua 5, 20018 Donostia/San Sebastián, Spain
- Donostia International Physics Center (DIPC), Manuel de Lardizabal pasealekua 4, 20018 Donostia/San Sebastián, Spain
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21
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Dutta M, Prasad MVD, Pandey J, Soni A, Waghmare UV, Biswas K. Local Symmetry Breaking Suppresses Thermal Conductivity in Crystalline Solids. Angew Chem Int Ed Engl 2022; 61:e202200071. [PMID: 35137508 DOI: 10.1002/anie.202200071] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Indexed: 11/07/2022]
Abstract
Understanding the correlations of both the local and global structures with lattice dynamics is critical for achieving low lattice thermal conductivity (κlat ) in crystalline materials. Herein, we demonstrate local cationic off-centring within the global rock-salt structure of AgSbSe2 by using synchrotron X-ray pair distribution function analysis and unravel the origin of its ultralow κlat ≈0.4 W mK-1 at 300 K. The cations are locally off-centered along the crystallographic ⟨ 100 ⟩ direction by about ≈0.2 Å, which averages out as the rock-salt structure on the global scale. Phonon dispersion obtained by density functional theory (DFT) shows weak instabilities that cause local off-centering distortions within an anharmonic double-well potential. The local structural distortion arises from the stereochemically active 5s2 lone pairs of Sb. Our findings open an avenue for understanding how the local structure influences the phonon transport and facilitates the design of next-generation crystalline materials with tailored thermal properties.
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Affiliation(s)
- Moinak Dutta
- New Chemistry Unit, School of Advanced Materials and International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore, 560064, India
| | - Matukumilli V D Prasad
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore, 560064, India
| | - Juhi Pandey
- School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh, 175005, India
| | - Ajay Soni
- School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh, 175005, India
| | - Umesh V Waghmare
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore, 560064, India
| | - Kanishka Biswas
- New Chemistry Unit, School of Advanced Materials and International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore, 560064, India
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22
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Local Symmetry Breaking Suppresses Thermal Conductivity in Crystalline Solids. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202200071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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23
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Cherubini M, Monacelli L, Mauri F. The microscopic origin of the anomalous isotopic properties of ice relies on the strong quantum anharmonic regime of atomic vibration. J Chem Phys 2021; 155:184502. [PMID: 34773945 DOI: 10.1063/5.0062689] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Water ice is a unique material presenting intriguing physical properties, such as negative thermal expansion and anomalous volume isotope effect (VIE). They arise from the interplay between weak hydrogen bonds and nuclear quantum fluctuations, making theoretical calculations challenging. Here, we employ the stochastic self-consistent harmonic approximation to investigate how thermal and quantum fluctuations affect the physical properties of ice XI with ab initio accuracy. Regarding the anomalous VIE, our work reveals that quantum effects on hydrogen are so strong to be in a nonlinear regime: When progressively increasing the mass of hydrogen from protium to infinity (classical limit), the volume first expands and then contracts, with a maximum slightly above the mass of tritium. We observe an anharmonic renormalization of about 10% in the bending and stretching phonon frequencies probed in IR and Raman experiments. For the first time, we report an accurate comparison of the low-energy phonon dispersion with the experimental data, possible only thanks to high-level accuracy in the electronic correlation and nuclear quantum and thermal fluctuations, paving the way for the study of thermal transport in ice from first-principles and the simulation of ice under pressure.
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Affiliation(s)
- Marco Cherubini
- Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Lorenzo Monacelli
- Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Francesco Mauri
- Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
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24
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Romanin D, Monacelli L, Bianco R, Errea I, Mauri F, Calandra M. Dominant Role of Quantum Anharmonicity in the Stability and Optical Properties of Infinite Linear Acetylenic Carbon Chains. J Phys Chem Lett 2021; 12:10339-10345. [PMID: 34664958 DOI: 10.1021/acs.jpclett.1c02964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Carbyne, an infinite-length straight chain of carbon atoms, is supposed to undergo a second order phase transition from the metallic bond-symmetric cumulene (═C═C═)∞ toward the distorted insulating polyyne chain (-C≡C-)∞ displaying bond-length alternation. However, recent synthesis of ultra long carbon chains (∼6000 atoms, [Nat. Mater., 2016, 15, 634]) did not show any phase transition and detected only the polyyne phase, in agreement with previous experiments on capped finite carbon chains. Here, by performing first-principles calculations, we show that quantum-anharmonicity reduces the energy gain of the polyyne phase with respect to the cumulene one by 71%. The magnitude of the bond-length alternation increases by increasing temperature, in stark contrast with a second order phase transition, confining the cumulene-to-polyyne transition to extremely high and unphysical temperatures. Finally, we predict that a high temperature insulator-to-metal transition occurs in the polyyne phase confined in insulating nanotubes with sufficiently large dielectric constant due to a giant quantum-anharmonic bandgap renormalization.
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Affiliation(s)
- Davide Romanin
- Institut des Nanosciences de Paris, UMR7588, Sorbonne Université, CNRS, F-75252, Paris, France
| | - Lorenzo Monacelli
- Dipartimento di Fisica, Universitá di Roma La Sapienza, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Raffaello Bianco
- Centro de Física de Materiales (CSIC-UPV/EHU), Manuel de Lardizabal pasealekua 5, 20018 Donostia-San Sebastián, Basque Country, Spain
| | - Ion Errea
- Centro de Física de Materiales (CSIC-UPV/EHU), Manuel de Lardizabal pasealekua 5, 20018 Donostia-San Sebastián, Basque Country, Spain
- Fisika Aplikatua 1 Saila, Gipuzkoako Ingeniaritza Eskola, University of the Basque Country (UPV/EHU), Europa Plaza 1, 20018, Donostia San Sebastián, Basque Country, Spain
| | - Francesco Mauri
- Dipartimento di Fisica, Universitá di Roma La Sapienza, Piazzale Aldo Moro 5, I-00185 Rome, Italy
| | - Matteo Calandra
- Institut des Nanosciences de Paris, UMR7588, Sorbonne Université, CNRS, F-75252, Paris, France
- Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo, Italy
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25
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Miotto M, Monacelli L. TOLOMEO, a Novel Machine Learning Algorithm to Measure Information and Order in Correlated Networks and Predict Their State. ENTROPY 2021; 23:e23091138. [PMID: 34573763 PMCID: PMC8470539 DOI: 10.3390/e23091138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 11/16/2022]
Abstract
We present ToloMEo (TOpoLogical netwOrk Maximum Entropy Optimization), a program implemented in C and Python that exploits a maximum entropy algorithm to evaluate network topological information. ToloMEo can study any system defined on a connected network where nodes can assume N discrete values by approximating the system probability distribution with a Pottz Hamiltonian on a graph. The software computes entropy through a thermodynamic integration from the mean-field solution to the final distribution. The nature of the algorithm guarantees that the evaluated entropy is variational (i.e., it always provides an upper bound to the exact entropy). The program also performs machine learning, inferring the system’s behavior providing the probability of unknown states of the network. These features make our method very general and applicable to a broad class of problems. Here, we focus on three different cases of study: (i) an agent-based model of a minimal ecosystem defined on a square lattice, where we show how topological entropy captures a crossover between hunting behaviors; (ii) an example of image processing, where starting from discretized pictures of cell populations we extract information about the ordering and interactions between cell types and reconstruct the most likely positions of cells when data are missing; and (iii) an application to recurrent neural networks, in which we measure the information stored in different realizations of the Hopfield model, extending our method to describe dynamical out-of-equilibrium processes.
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Affiliation(s)
- Mattia Miotto
- Department of Physics, Sapienza University of Rome, 00184 Rome, Italy
- Center for Life Nano- & Neuro Science, Istituto Italiano di Tecnologia, 00161 Rome, Italy
- Correspondence: (M.M.); (L.M.)
| | - Lorenzo Monacelli
- Department of Physics, Sapienza University of Rome, 00184 Rome, Italy
- Correspondence: (M.M.); (L.M.)
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