1
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Tao YL, Liu QJ, Fan DH, Liu FS, Liu ZT. Emerging superconductivity rules in rare-earth and alkaline-earth metal hydrides. iScience 2024; 27:110542. [PMID: 39184437 PMCID: PMC11342274 DOI: 10.1016/j.isci.2024.110542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 07/03/2024] [Accepted: 07/16/2024] [Indexed: 08/27/2024] Open
Abstract
Hydrides of alkaline-earth and rare-earth metals have garnered significant interest in high-temperature superconductor research due to their excellent electron-phonon coupling and high T c upon pressurization. This study explores the electronic structures and electron-phonon coupling of metal hydrides XHn (n = 4,6), where X includes Ca, Mg, Sc, and Y. The involvement of d-orbital electrons alters the Fermi surface, leading to saddle-point nesting and a charge density wave (CDW) phase transition, which opens the superconducting gap. For instance, in YH6, the exchange coupling between Y-4d and H-1s holes in the phonon softening region results in T c values up to 230 K. The study suggests that factors, such as the origin of the CDW order, hydrogen concentration, and d-orbital contributions are crucial to superconductivity. This work proposes a new rule for high T c superconductors, emphasizing the importance of double gaps and electron-phonon interactions at exchange coupling sites, and predicts potential high-quality superconductors among rare-earth hydrides.
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Affiliation(s)
- Ya-Le Tao
- Bond and Band Engineering Group, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
| | - Qi-Jun Liu
- Bond and Band Engineering Group, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
| | - Dai-He Fan
- Bond and Band Engineering Group, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
| | - Fu-Sheng Liu
- Bond and Band Engineering Group, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
| | - Zheng-Tang Liu
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, People’s Republic of China
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2
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Li C. High-pressure structures of solid hydrogen: Insights from ab initio molecular dynamics simulations. J Chem Phys 2024; 160:144302. [PMID: 38587224 DOI: 10.1063/5.0198080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 03/19/2024] [Indexed: 04/09/2024] Open
Abstract
Understanding the structural behavior of solid hydrogen under high pressures is crucial for uncovering its unique properties and potential applications. In this study, starting from the phase I of solid hydrogen-free-rotator hcp structure, we conduct extensive ab initio molecular dynamics calculations to simulate the cooling, heating, and equilibrium processes within a pressure range of 80-260 GPa. Without relying on any structure previously predicted, we identify the high-pressure phase structures of solid hydrogen as P21/c for phase II, P6522 for phase III, and BG1BG2BG3 six-layer structure for phase IV, which are different from those proposed previously using the structure-search method. The reasonability of these structures are validated by Raman spectra and x-ray diffraction patterns by comparison with the experimental results. Our results actually show pronounced changes in the c/a ratio between phases I, III, and IV, which hold no brief for the experimental interpretation of an isostructural hcp transformations for phases I-III-IV.
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Affiliation(s)
- Cong Li
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, People's Republic of China and Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application, School of Physical Science and Technology, Suzhou University of Science and Technology, Suzhou 215009, China
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3
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Loa I, Landgren F. On: X-ray diffraction from the electron gas in monatomic metallic hydrogen. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:185401. [PMID: 38215491 DOI: 10.1088/1361-648x/ad1e08] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 01/12/2024] [Indexed: 01/14/2024]
Abstract
Solid hydrogen is expected to become a monatomic metal under sufficiently high compression. With hydrogen having only a single valence electron and no ion core, the nature of x-ray diffraction patterns from the electron gas of monatomic metallic hydrogen is uncertain, and it is unclear whether they may yield enough information for a crystal structure determination. With emphasis on the Cs-IV-type (I41/amd) structure predicted for hydrogen at ∼500 GPa, the electron density distributions, zero-point and thermal atomic motion, and x-ray diffraction intensities are determined from first-principles calculations for several candidate phases of metallic hydrogen. It is shown that the electron distribution is much more structured than might be expected from the commonly employed free-electron-gas picture, and in fact more modulated than what is obtained from the superposition of free-atom charge densities. We demonstrate that an identification of the crystal structure of monatomic metallic hydrogen from x-ray diffraction is fundamentally possible and discuss the possibility of single-crystal diffraction from metallic hydrogen. An atomic scattering factor for the hydrogen atom in monatomic metallic hydrogen is constructed to aid the quantitative analysis of diffraction intensities from future x-ray diffraction experiments.
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Affiliation(s)
- Ingo Loa
- SUPA, School of Physics and Astronomy and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - Filip Landgren
- SUPA, School of Physics and Astronomy and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
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4
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Shi X, Gao J, Qiu S, Chang Y, Zhao L, Fu ZG, Zhao J, Zhang P. Stability and superconductivity of freestanding two-dimensional transition metal boridene: M 4/3B 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 36:085602. [PMID: 37939399 DOI: 10.1088/1361-648x/ad0ace] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 11/08/2023] [Indexed: 11/10/2023]
Abstract
The small atomic mass of boron indicates strong electron-phonon coupling (EPC), so it may have a brilliant performance in superconductivity. Recently, a new 2D boride sheet with ordered metal vacancies and surface terminals (Mo4/3B2-x) was realized in experiments (Zhouet al2021Science373801). Here, the 2D monolayer freestanding Mo4/3B2is evidenced to be thermodynamically stable. Through electronic structure, phonon spectrum and EPC, monolayer Mo4/3B2is found to be an intrinsic phonon-mediated superconductor. The superconducting transition temperature (Tc) is determined to be 4.06 K by the McMillian-Allen-Dynes formula. Remarkably, theTcof monolayer Mo4/3B2can be increased to 6.78 K with an appropriate biaxial tensile strain (+5%). Moreover, we predict that other transition metal replacing Mo atoms is also stable and retaining the superconductivity. Such as monolayer W4/3B2is also a superconductor with theTcof 2.37 K. Our research results enrich the database of 2D monolayer superconductors and boron-related formed materials science.
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Affiliation(s)
- Xiaoran Shi
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, People's Republic of China
| | - Junfeng Gao
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, People's Republic of China
| | - Shi Qiu
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, People's Republic of China
| | - Yuan Chang
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, People's Republic of China
| | - Luneng Zhao
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, People's Republic of China
| | - Zhen-Guo Fu
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, People's Republic of China
| | - Jijun Zhao
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, People's Republic of China
| | - Ping Zhang
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, People's Republic of China
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5
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Myung CW, Hirshberg B, Parrinello M. Prediction of a Supersolid Phase in High-Pressure Deuterium. PHYSICAL REVIEW LETTERS 2022; 128:045301. [PMID: 35148160 DOI: 10.1103/physrevlett.128.045301] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 08/20/2021] [Accepted: 12/15/2021] [Indexed: 06/14/2023]
Abstract
Supersolid is a mysterious and puzzling state of matter whose possible existence has stirred a vigorous debate among physicists for over 60 years. Its elusive nature stems from the coexistence of two seemingly contradicting properties, long-range order and superfluidity. We report computational evidence of a supersolid phase of deuterium under high pressure (p>800 GPa) and low temperature (T<1.0 K). In our simulations, that are based on bosonic path integral molecular dynamics, we observe a highly concerted exchange of atoms while the system preserves its crystalline order. The exchange processes are favored by the soft core interactions between deuterium atoms that form a densely packed metallic solid. At the zero temperature limit, Bose-Einstein condensation is observed as the permutation probability of N deuterium atoms approaches 1/N with a finite superfluid fraction. Our study provides concrete evidence for the existence of a supersolid phase in high-pressure deuterium and could provide insights on the future investigation of supersolid phases in real materials.
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Affiliation(s)
- Chang Woo Myung
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lenseld Road, Cambridge, CB2 1EW, United Kingdom
| | - Barak Hirshberg
- School of Chemistry, Tel Aviv University, Tel Aviv 6997801, Israel
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6
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Chen W, Semenok DV, Huang X, Shu H, Li X, Duan D, Cui T, Oganov AR. High-Temperature Superconducting Phases in Cerium Superhydride with a T_{c} up to 115 K below a Pressure of 1 Megabar. PHYSICAL REVIEW LETTERS 2021; 127:117001. [PMID: 34558917 DOI: 10.1103/physrevlett.127.117001] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 07/30/2021] [Indexed: 05/25/2023]
Abstract
The discoveries of high-temperature superconductivity in H_{3}S and LaH_{10} have excited the search for superconductivity in compressed hydrides, finally leading to the first discovery of a room-temperature superconductor in a carbonaceous sulfur hydride. In contrast to rapidly expanding theoretical studies, high-pressure experiments on hydride superconductors are expensive and technically challenging. Here, we experimentally discovered superconductivity in two new phases, Fm3[over ¯]m-CeH_{10} (SC-I phase) and P6_{3}/mmc-CeH_{9} (SC-II phase) at pressures that are much lower (<100 GPa) than those needed to stabilize other polyhydride superconductors. Superconductivity was evidenced by a sharp drop of the electrical resistance to zero and decreased critical temperature in deuterated samples and in external magnetic field. SC-I has T_{c}=115 K at 95 GPa, showing an expected decrease in further compression due to the decrease of the electron-phonon coupling (EPC) coefficient λ (from 2.0 at 100 GPa to 0.8 at 200 GPa). SC-II has T_{c}=57 K at 88 GPa, rapidly increasing to a maximum T_{c}∼100 K at 130 GPa, and then decreasing in further compression. According to the theoretical calculation, this is due to a maximum of λ at the phase transition from P6_{3}/mmc-CeH_{9} into a symmetry-broken modification C2/c-CeH_{9}. The pressure-temperature conditions of synthesis affect the actual hydrogen content and the actual value of T_{c}. Anomalously low pressures of stability of cerium superhydrides make them appealing for studies of superhydrides and for designing new superhydrides with stability at even lower pressures.
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Affiliation(s)
- Wuhao Chen
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Dmitrii V Semenok
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, Bolshoy Boulevard 30, bldg. 1 Moscow, Russia 121205
| | - Xiaoli Huang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Haiyun Shu
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
| | - Xin Li
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Defang Duan
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Tian Cui
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
| | - Artem R Oganov
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, Bolshoy Boulevard 30, bldg. 1 Moscow, Russia 121205
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7
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Monacelli L, Bianco R, Cherubini M, Calandra M, Errea I, Mauri F. The stochastic self-consistent harmonic approximation: calculating vibrational properties of materials with full quantum and anharmonic effects. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:363001. [PMID: 34049302 DOI: 10.1088/1361-648x/ac066b] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 05/28/2021] [Indexed: 06/12/2023]
Abstract
The efficient and accurate calculation of how ionic quantum and thermal fluctuations impact the free energy of a crystal, its atomic structure, and phonon spectrum is one of the main challenges of solid state physics, especially when strong anharmonicy invalidates any perturbative approach. To tackle this problem, we present the implementation on a modular Python code of the stochastic self-consistent harmonic approximation (SSCHA) method. This technique rigorously describes the full thermodynamics of crystals accounting for nuclear quantum and thermal anharmonic fluctuations. The approach requires the evaluation of the Born-Oppenheimer energy, as well as its derivatives with respect to ionic positions (forces) and cell parameters (stress tensor) in supercells, which can be provided, for instance, by first principles density-functional-theory codes. The method performs crystal geometry relaxation on the quantum free energy landscape, optimizing the free energy with respect to all degrees of freedom of the crystal structure. It can be used to determine the phase diagram of any crystal at finite temperature. It enables the calculation of phase boundaries for both first-order and second-order phase transitions from the Hessian of the free energy. Finally, the code can also compute the anharmonic phonon spectra, including the phonon linewidths, as well as phonon spectral functions. We review the theoretical framework of the SSCHA and its dynamical extension, making particular emphasis on the physical inter pretation of the variables present in the theory that can enlighten the comparison with any other anharmonic theory. A modular and flexible Python environment is used for the implementation, which allows for a clean interaction with other packages. We briefly present a toy-model calculation to illustrate the potential of the code. Several applications of the method in superconducting hydrides, charge-density-wave materials, and thermoelectric compounds are also reviewed.
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Affiliation(s)
- Lorenzo Monacelli
- Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Raffaello Bianco
- Centro de Física de Materiales (CSIC-UPV/EHU), Manuel de Lardizabal pasealekua 5, 20018 Donostia/San Sebastián, Spain
| | - Marco Cherubini
- Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy
- Center for Life NanoScience, Istituto Italiano di Tecnologia, Viale ReginaElena 291, 00161 Rome, Italy
| | - Matteo Calandra
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252 Paris, France
- Dipartimento di Fisica, Universitá di Trento, Via Sommarive 14, 38123 Povo, Italy
| | - Ion Errea
- Centro de Física de Materiales (CSIC-UPV/EHU), Manuel de Lardizabal pasealekua 5, 20018 Donostia/San Sebastián, Spain
- Fisika Aplikatua Saila, Gipuzkoako Ingeniaritza Eskola, University of the Basque Country (UPV/EHU), Europa Plaza 1, 20018 Donostia/San Sebastián, Spain
- Donostia International Physics Center (DIPC), Manuel Lardizabal pasealekua 4, 20018 Donostia/San Sebastián, Spain
| | - Francesco Mauri
- Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy
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8
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Kheirmand M, Heydari N, Azami SM. Electronic structure, thermodynamic properties and metallic behaviours of hydrogen. Mol Phys 2021. [DOI: 10.1080/00268976.2020.1810350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Mahdi Kheirmand
- Department of Chemistry, Faculty of science, Yasouj University, Yasouj, Iran
| | - Neda Heydari
- Department of Chemistry, Faculty of science, Yasouj University, Yasouj, Iran
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9
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Chen W, Semenok DV, Kvashnin AG, Huang X, Kruglov IA, Galasso M, Song H, Duan D, Goncharov AF, Prakapenka VB, Oganov AR, Cui T. Synthesis of molecular metallic barium superhydride: pseudocubic BaH 12. Nat Commun 2021; 12:273. [PMID: 33431840 PMCID: PMC7801595 DOI: 10.1038/s41467-020-20103-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 11/13/2020] [Indexed: 01/29/2023] Open
Abstract
Following the discovery of high-temperature superconductivity in the La-H system, we studied the formation of new chemical compounds in the barium-hydrogen system at pressures from 75 to 173 GPa. Using in situ generation of hydrogen from NH3BH3, we synthesized previously unknown superhydride BaH12 with a pseudocubic (fcc) Ba sublattice in four independent experiments. Density functional theory calculations indicate close agreement between the theoretical and experimental equations of state. In addition, we identified previously known P6/mmm-BaH2 and possibly BaH10 and BaH6 as impurities in the samples. Ab initio calculations show that newly discovered semimetallic BaH12 contains H2 and H3- molecular units and detached H12 chains which are formed as a result of a Peierls-type distortion of the cubic cage structure. Barium dodecahydride is a unique molecular hydride with metallic conductivity that demonstrates the superconducting transition around 20 K at 140 GPa.
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Affiliation(s)
- Wuhao Chen
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, China
| | - Dmitrii V Semenok
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 143026, Russia
| | - Alexander G Kvashnin
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 143026, Russia
| | - Xiaoli Huang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, China.
| | - Ivan A Kruglov
- Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny, 141700, Russia
- Dukhov Research Institute of Automatics (VNIIA), Moscow, 127055, Russia
| | - Michele Galasso
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 143026, Russia
| | - Hao Song
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, China
| | - Defang Duan
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, China
| | - Alexander F Goncharov
- Earth and Planets Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, DC, 20015, USA
| | - Vitali B Prakapenka
- Center for Advanced Radiation Sources, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL, 60637, USA
| | - Artem R Oganov
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 143026, Russia.
| | - Tian Cui
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, China.
- School of Physical Science and Technology, Ningbo University, Ningbo, 315211, China.
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10
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Engel EA. Identification of synthesisable crystalline phases of water – a prototype for the challenges of computational materials design. CrystEngComm 2021. [DOI: 10.1039/d0ce01260b] [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
We discuss the identification of experimentally realisable crystalline phases of water to outline and contextualise some of the diverse building blocks of a computational materials design process.
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Affiliation(s)
- Edgar A. Engel
- TCM Group
- Cavendish Laboratory
- University of Cambridge
- Cambridge CB3 0HE
- UK
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11
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Silvera IF, Dias R. Phases of the hydrogen isotopes under pressure: metallic hydrogen. ADVANCES IN PHYSICS: X 2021. [DOI: 10.1080/23746149.2021.1961607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Affiliation(s)
| | - Ranga Dias
- Department of Physics and Astronomy and Mechanical Engineering, University of Rochester, Rochester, USA
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12
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Azadi S, Booth GH, Kühne TD. Equation of state of atomic solid hydrogen by stochastic many-body wave function methods. J Chem Phys 2020; 153:204107. [DOI: 10.1063/5.0026499] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Sam Azadi
- Department of Physics, King’s College London, Strand, WC2R 2LS London, United Kingdom
| | - George H. Booth
- Department of Physics, King’s College London, Strand, WC2R 2LS London, United Kingdom
| | - Thomas D. Kühne
- Department of Chemistry, Paderborn Center for Parallel Computing, Paderborn University, 33098 Paderborn, Germany
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13
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Trachenko K, Monserrat B, Pickard CJ, Brazhkin VV. Speed of sound from fundamental physical constants. SCIENCE ADVANCES 2020; 6:6/41/eabc8662. [PMID: 33036979 PMCID: PMC7546695 DOI: 10.1126/sciadv.abc8662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 08/27/2020] [Indexed: 05/25/2023]
Abstract
Two dimensionless fundamental physical constants, the fine structure constant α and the proton-to-electron mass ratio [Formula: see text], are attributed a particular importance from the point of view of nuclear synthesis, formation of heavy elements, planets, and life-supporting structures. Here, we show that a combination of these two constants results in a new dimensionless constant that provides the upper bound for the speed of sound in condensed phases, vu We find that [Formula: see text], where c is the speed of light in vacuum. We support this result by a large set of experimental data and first-principles computations for atomic hydrogen. Our result expands the current understanding of how fundamental constants can impose new bounds on important physical properties.
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Affiliation(s)
- K Trachenko
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
| | - B Monserrat
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - C J Pickard
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK
- Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
| | - V V Brazhkin
- Institute for High Pressure Physics, RAS, 108840 Troitsk, Moscow, Russia.
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14
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Needs RJ, Towler MD, Drummond ND, López Ríos P, Trail JR. Variational and diffusion quantum Monte Carlo calculations with the CASINO code. J Chem Phys 2020; 152:154106. [DOI: 10.1063/1.5144288] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- R. J. Needs
- TCM Group, Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - M. D. Towler
- University College London, London WC1E 6BT, United Kingdom
| | - N. D. Drummond
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - P. López Ríos
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - J. R. Trail
- TCM Group, Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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15
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Gorelov V, Holzmann M, Ceperley DM, Pierleoni C. Energy Gap Closure of Crystalline Molecular Hydrogen with Pressure. PHYSICAL REVIEW LETTERS 2020; 124:116401. [PMID: 32242714 DOI: 10.1103/physrevlett.124.116401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 02/13/2020] [Indexed: 06/11/2023]
Abstract
We study the gap closure with pressure of crystalline molecular hydrogen. The gaps are obtained from grand-canonical quantum Monte Carlo methods properly extended to quantum and thermal crystals, simulated by coupled electron ion Monte Carlo methods. Nuclear zero point effects cause a large reduction in the gap (∼2 eV). Depending on the structure, the fundamental indirect gap closes between 380 and 530 GPa for ideal crystals and 330-380 GPa for quantum crystals. Beyond this pressure the system enters into a bad metal phase where the density of states at the Fermi level increases with pressure up to ∼450-500 GPa when the direct gap closes. Our work partially supports the interpretation of recent experiments in high pressure hydrogen.
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Affiliation(s)
- Vitaly Gorelov
- Université Paris-Saclay, UVSQ, CNRS, CEA, Maison de la Simulation, 91191, Gif-sur-Yvette, France
| | - Markus Holzmann
- Univ. Grenoble Alpes, CNRS, LPMMC, 38000 Grenoble, France
- Institut Laue-Langevin, BP 156, F-38042 Grenoble Cedex 9, France
| | - David M Ceperley
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Carlo Pierleoni
- Université Paris-Saclay, UVSQ, CNRS, CEA, Maison de la Simulation, 91191, Gif-sur-Yvette, France
- Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio 10, I-67010 L'Aquila, Italy
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16
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Cui TT, Li JC, Gao W, Hermann J, Tkatchenko A, Jiang Q. Nonlocal Electronic Correlations in the Cohesive Properties of High-Pressure Hydrogen Solids. J Phys Chem Lett 2020; 11:1521-1527. [PMID: 32031376 DOI: 10.1021/acs.jpclett.9b03716] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
High-pressure hydrogen exhibits remarkable phenomena including the insulator-to-metal (IM) transition; however, a complete resolution of its phase diagram is still an elusive goal despite many efforts and much controversy. Theoretical modeling is typically based on density functional theory (DFT) with a mean-field description of electronic correlations, which is known to be rather limited in describing IM transitions. Herein, we show that nonlocal electron correlations play a central role in the relative stability of solid hydrogen phases, and that DFT-correcting for these correlations by the many-body dispersion (MBD) model reaches the accuracy of quantum Monte Carlo (QMC) simulations and predicts the same C2/c-24 → Cmca-12 → Cs(IV) IM transition. In contrast with the conventional assumption that many-body electronic correlations become localized in metallic systems because of exponential screening with interelectronic distance, we find that the anisotropy of the electronic response of hydrogen solids under pressure leads to longer-ranged many-body effects in metallic phases relative to insulating ones. This refines our understanding of phase diagram of hydrogen solids as well as anisotropic many-body correlations.
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Affiliation(s)
- Ting-Ting Cui
- Key Laboratory of Automobile Materials (Jilin University), Ministry of Education, Department of Materials Science and Engineering , Jilin University , Changchun 130022 , China
| | - Jian-Chen Li
- Key Laboratory of Automobile Materials (Jilin University), Ministry of Education, Department of Materials Science and Engineering , Jilin University , Changchun 130022 , China
| | - Wang Gao
- Key Laboratory of Automobile Materials (Jilin University), Ministry of Education, Department of Materials Science and Engineering , Jilin University , Changchun 130022 , China
| | - Jan Hermann
- Physics and Materials Science Research Unit , University of Luxembourg , L-1511 Luxembourg City , Luxembourg
| | - Alexandre Tkatchenko
- Physics and Materials Science Research Unit , University of Luxembourg , L-1511 Luxembourg City , Luxembourg
| | - Qing Jiang
- Key Laboratory of Automobile Materials (Jilin University), Ministry of Education, Department of Materials Science and Engineering , Jilin University , Changchun 130022 , China
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17
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Zhou D, Semenok DV, Xie H, Huang X, Duan D, Aperis A, Oppeneer PM, Galasso M, Kartsev AI, Kvashnin AG, Oganov AR, Cui T. High-Pressure Synthesis of Magnetic Neodymium Polyhydrides. J Am Chem Soc 2020; 142:2803-2811. [DOI: 10.1021/jacs.9b10439] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Di Zhou
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Dmitrii V. Semenok
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow 121205, Russia
| | - Hui Xie
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Xiaoli Huang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Defang Duan
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Alex Aperis
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, Uppsala SE-75120, Sweden
| | - Peter M. Oppeneer
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, Uppsala SE-75120, Sweden
| | - Michele Galasso
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow 121205, Russia
| | - Alexey I. Kartsev
- Computing Center of Far Eastern Branch of the Russian Academy of Sciences (CC FEB RAS), Khabarovsk 680000, Russian Federation
- School of Mathematics and Physics, Queen’s University Belfast, Belfast, Northern Ireland BT7 1NN, United Kingdom
| | - Alexander G. Kvashnin
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow 121205, Russia
| | - Artem R. Oganov
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow 121205, Russia
- International Center for Materials Discovery, Northwestern Polytechnical University, Xi’an 710072, China
| | - Tian Cui
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
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18
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Zen A, Brandenburg JG, Michaelides A, Alfè D. A new scheme for fixed node diffusion quantum Monte Carlo with pseudopotentials: Improving reproducibility and reducing the trial-wave-function bias. J Chem Phys 2019; 151:134105. [DOI: 10.1063/1.5119729] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Andrea Zen
- Thomas Young Centre, University College London, London WC1H 0AH, United Kingdom
- London Centre for Nanotechnology, Gordon St., London WC1H 0AH, United Kingdom
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
- Department of Earth Sciences, University College London, London WC1E 6BT, United Kingdom
| | - Jan Gerit Brandenburg
- Thomas Young Centre, University College London, London WC1H 0AH, United Kingdom
- Interdisciplinary Center for Scientific Computing, University of Heidelberg, Im Neuenheimer Feld 205A, 69120 Heidelberg, Germany
| | - Angelos Michaelides
- Thomas Young Centre, University College London, London WC1H 0AH, United Kingdom
- London Centre for Nanotechnology, Gordon St., London WC1H 0AH, United Kingdom
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Dario Alfè
- Thomas Young Centre, University College London, London WC1H 0AH, United Kingdom
- London Centre for Nanotechnology, Gordon St., London WC1H 0AH, United Kingdom
- Department of Earth Sciences, University College London, London WC1E 6BT, United Kingdom
- Dipartimento di Fisica Ettore Pancini, Università di Napoli Federico II, Monte S. Angelo, I-80126 Napoli, Italy
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19
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Salke NP, Davari Esfahani MM, Zhang Y, Kruglov IA, Zhou J, Wang Y, Greenberg E, Prakapenka VB, Liu J, Oganov AR, Lin JF. Synthesis of clathrate cerium superhydride CeH 9 at 80-100 GPa with atomic hydrogen sublattice. Nat Commun 2019; 10:4453. [PMID: 31575861 PMCID: PMC6773858 DOI: 10.1038/s41467-019-12326-y] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 08/28/2019] [Indexed: 11/10/2022] Open
Abstract
Hydrogen-rich superhydrides are believed to be very promising high-Tc superconductors. Recent experiments discovered superhydrides at very high pressures, e.g. FeH5 at 130 GPa and LaH10 at 170 GPa. With the motivation of discovering new hydrogen-rich high-Tc superconductors at lowest possible pressure, here we report the prediction and experimental synthesis of cerium superhydride CeH9 at 80–100 GPa in the laser-heated diamond anvil cell coupled with synchrotron X-ray diffraction. Ab initio calculations were carried out to evaluate the detailed chemistry of the Ce-H system and to understand the structure, stability and superconductivity of CeH9. CeH9 crystallizes in a P63/mmc clathrate structure with a very dense 3-dimensional atomic hydrogen sublattice at 100 GPa. These findings shed a significant light on the search for superhydrides in close similarity with atomic hydrogen within a feasible pressure range. Discovery of superhydride CeH9 provides a practical platform to further investigate and understand conventional superconductivity in hydrogen rich superhydrides. Hydrogen-rich superhydrides are promising high-temperature superconductors which have been observed only at pressures above 170 GPa. Here the authors show that CeH9 can be synthesized at 80-100 GPa with laser heating, and is characterized by a clathrate structure with a dense 3-dimensional atomic hydrogen sublattice.
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Affiliation(s)
- Nilesh P Salke
- Center for High Pressure Science & Technology Advanced Research (HPSTAR), 100094, Beijing, China
| | - M Mahdi Davari Esfahani
- Department of Geosciences, Center for Materials by Design, and Institute for Advanced Computational Science, State University of New York, Stony Brook, New York, NY, 11794-2100, USA
| | - Youjun Zhang
- Institute of Atomic and Molecular Physics, Sichuan University, 610065, Chengdu, China
| | - Ivan A Kruglov
- Department of Problems of Physics and Energetics, Moscow Institute of Physics and Technology, 9 Institutskiy Lane, Dolgoprudny City, Moscow Region, 141700, Russia.,Dukhov Research Institute of Automatics (VNIIA), Moscow, 127055, Russia
| | - Jianshi Zhou
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Yaguo Wang
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Eran Greenberg
- Center for Advanced Radiation Sources, University of Chicago, Chicago, 60637, IL, USA
| | - Vitali B Prakapenka
- Center for Advanced Radiation Sources, University of Chicago, Chicago, 60637, IL, USA
| | - Jin Liu
- Center for High Pressure Science & Technology Advanced Research (HPSTAR), 100094, Beijing, China
| | - Artem R Oganov
- Department of Problems of Physics and Energetics, Moscow Institute of Physics and Technology, 9 Institutskiy Lane, Dolgoprudny City, Moscow Region, 141700, Russia. .,Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 143026, Russia. .,International Center for Materials Design, Northwestern Polytechnical University, 710072, Xi'an, China.
| | - Jung-Fu Lin
- Department of Geological Sciences, The University of Texas at Austin, Austin, TX, 78712, USA.
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20
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Kapil V, Engel E, Rossi M, Ceriotti M. Assessment of Approximate Methods for Anharmonic Free Energies. J Chem Theory Comput 2019; 15:5845-5857. [DOI: 10.1021/acs.jctc.9b00596] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Venkat Kapil
- Laboratory of Computational Science and Modeling, Institut des Matériaux, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Edgar Engel
- Laboratory of Computational Science and Modeling, Institut des Matériaux, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Mariana Rossi
- Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany
| | - Michele Ceriotti
- Laboratory of Computational Science and Modeling, Institut des Matériaux, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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21
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Bekaert J, Petrov M, Aperis A, Oppeneer PM, Milošević MV. Hydrogen-Induced High-Temperature Superconductivity in Two-Dimensional Materials: The Example of Hydrogenated Monolayer MgB_{2}. PHYSICAL REVIEW LETTERS 2019; 123:077001. [PMID: 31491112 DOI: 10.1103/physrevlett.123.077001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 04/23/2019] [Indexed: 06/10/2023]
Abstract
Hydrogen-based compounds under ultrahigh pressure, such as the polyhydrides H_{3}S and LaH_{10}, superconduct through the conventional electron-phonon coupling mechanism to attain the record critical temperatures known to date. Here we exploit the intrinsic advantages of hydrogen to strongly enhance phonon-mediated superconductivity in a completely different system, namely, a two-dimensional material with hydrogen adatoms. We find that van Hove singularities in the electronic structure, originating from atomiclike hydrogen states, lead to a strong increase of the electronic density of states at the Fermi level, and thus of the electron-phonon coupling. Additionally, the emergence of high-frequency hydrogen-related phonon modes in this system boosts the electron-phonon coupling further. As a concrete example, we demonstrate the effect of hydrogen adatoms on the superconducting properties of monolayer MgB_{2}, by solving the fully anisotropic Eliashberg equations, in conjunction with a first-principles description of the electronic and vibrational states, and their coupling. We show that hydrogenation leads to a high critical temperature of 67 K, which can be boosted to over 100 K by biaxial tensile strain.
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Affiliation(s)
- J Bekaert
- Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - M Petrov
- Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - A Aperis
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden
| | - P M Oppeneer
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden
| | - M V Milošević
- Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
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22
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Monserrat B, Ashbrook SE, Pickard CJ. Nuclear Magnetic Resonance Spectroscopy as a Dynamical Structural Probe of Hydrogen under High Pressure. PHYSICAL REVIEW LETTERS 2019; 122:135501. [PMID: 31012613 DOI: 10.1103/physrevlett.122.135501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Indexed: 06/09/2023]
Abstract
An unambiguous crystallographic structure solution for the observed phases II-VI of high pressure hydrogen does not exist due to the failure of standard structural probes at extreme pressure. In this work we propose that nuclear magnetic resonance spectroscopy provides a complementary structural probe for high pressure hydrogen. We show that the best structural models available for phases II, III, and IV of high pressure hydrogen exhibit markedly distinct nuclear magnetic resonance spectra which could therefore be used to discriminate amongst them. As an example, we demonstrate how nuclear magnetic resonance spectroscopy could be used to establish whether phase III exhibits polymorphism. Our calculations also reveal a strong renormalization of the nuclear magnetic resonance response in hydrogen arising from quantum fluctuations, as well as a strong isotope effect. As the experimental techniques develop, nuclear magnetic resonance spectroscopy can be expected to become a useful complementary structural probe in high pressure experiments.
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Affiliation(s)
- Bartomeu Monserrat
- TCM Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Sharon E Ashbrook
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom
| | - Chris J Pickard
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
- Advanced Institute for Materials Research, Tohoku University 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan
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23
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Silvera IF, Dias R. Metallic hydrogen. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:254003. [PMID: 29749966 DOI: 10.1088/1361-648x/aac401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Hydrogen is the simplest and most abundant element in the Universe. There are two pathways for creating metallic hydrogen under high pressures. Over 80 years ago Wigner and Huntington predicted that if solid molecular hydrogen was sufficiently compressed in the T = 0 K limit, molecules would dissociate to form atomic metallic hydrogen (MH). We have observed this transition at a pressure of 4.95 megabars. MH in this form has probably never existed on Earth or in the Universe; it may be a room temperature superconductor and is predicted to be metastable. If metastable it will have an important technological impact. Liquid metallic hydrogen can also be produced at intermediate pressures and high temperatures and is believed to make up ~90% of the planet Jupiter. We have observed this liquid-liquid transition, also known as the plasma phase transition, at pressures of ~1-2 megabar and temperatures ~1000-2000 K. However, in this paper we shall focus on the Wigner-Huntington transition. We shall discuss the methods used to observe metallic hydrogen at extreme conditions of static pressure in the laboratory, extending our understanding of the phase diagram of the simplest atom in the periodic table.
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Affiliation(s)
- Isaac F Silvera
- Lyman Laboratory of Physics, Harvard University, Cambridge, MA 02138, United States of America
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24
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Monserrat B, Drummond ND, Dalladay-Simpson P, Howie RT, López Ríos P, Gregoryanz E, Pickard CJ, Needs RJ. Structure and Metallicity of Phase V of Hydrogen. PHYSICAL REVIEW LETTERS 2018; 120:255701. [PMID: 29979086 DOI: 10.1103/physrevlett.120.255701] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 05/17/2018] [Indexed: 06/08/2023]
Abstract
A new phase V of hydrogen was recently claimed in experiments above 325 GPa and 300 K. Because of the extremely small sample size at such record pressures the measurements were limited to Raman spectroscopy. The experimental data on increase of pressure show decreasing Raman activity and darkening of the sample, which suggests band gap closure and impending molecular dissociation, but no definite conclusions could be reached. Furthermore, the available data are insufficient to determine the structure of phase V, which remains unknown. Introducing saddle-point ab initio random structure searching, we find several new structural candidates of hydrogen which could describe the observed properties of phase V. We investigate hydrogen metallization in the proposed candidate structures, and demonstrate that smaller band gaps are associated with longer bond lengths. We conclude that phase V is a stepping stone towards metallization.
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Affiliation(s)
- Bartomeu Monserrat
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019, USA
- TCM Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Neil D Drummond
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Philip Dalladay-Simpson
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, People's Republic of China
| | - Ross T Howie
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, People's Republic of China
| | - Pablo López Ríos
- TCM Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- Max-Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Eugene Gregoryanz
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, People's Republic of China
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Chris J Pickard
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
- Advanced Institute for Materials Research, Tohoku University 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | - Richard J Needs
- TCM Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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25
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Rillo G, Morales MA, Ceperley DM, Pierleoni C. Coupled electron-ion Monte Carlo simulation of hydrogen molecular crystals. J Chem Phys 2018; 148:102314. [DOI: 10.1063/1.5001387] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Giovanni Rillo
- Department of Physics, Sapienza University of Rome, Rome, Italy
| | - Miguel A. Morales
- Physics Division, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - David M. Ceperley
- Department of Physics, University of Illinois Urbana-Champaign, Champaign, llinois 61801, USA
| | - Carlo Pierleoni
- Department of Physical and Chemical Sciences, University of L’Aquila, L’Aquila, Italy
- Maison de la Simulation, CEA, CNRS, Univ. Paris-Sud, UVSQ, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
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26
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Borinaga M, Ibañez-Azpiroz J, Bergara A, Errea I. Strong Electron-Phonon and Band Structure Effects in the Optical Properties of High Pressure Metallic Hydrogen. PHYSICAL REVIEW LETTERS 2018; 120:057402. [PMID: 29481166 DOI: 10.1103/physrevlett.120.057402] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Indexed: 06/08/2023]
Abstract
The recent claim of having produced metallic hydrogen in the laboratory relies on measurements of optical spectra. Here, we present first-principles calculations of the reflectivity of hydrogen between 400 and 600 GPa in the I4_{1}/amd crystal structure, the one predicted at these pressures, based on both time-dependent density functional and Eliashberg theories, thus, covering the optical properties from the infrared to the ultraviolet regimes. Our results show that atomic hydrogen displays an interband plasmon at around 6 eV that abruptly suppresses the reflectivity, while the large superconducting gap energy yields a sharp decrease of the reflectivity in the infrared region approximately at 120 meV. The experimentally estimated electronic scattering rates in the 0.7-3 eV range are in agreement with our theoretical estimations, which show that the huge electron-phonon interaction of the system dominates the electronic scattering in this energy range. The remarkable features in the optical spectra predicted here encourage extending the optical measurements to the infrared and ultraviolet regions as our results suggest optical measurements can potentially identify high-pressure phases of hydrogen.
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Affiliation(s)
- Miguel Borinaga
- Centro de Física de Materiales CFM, CSIC-UPV/EHU, Manuel Lardizabal Pasealekua 5, 20018 Donostia/San Sebastián, Basque Country, Spain
- Donostia International Physics Center (DIPC), Manuel Lardizabal Pasealekua 4, 20018 Donostia/San Sebastián, Basque Country, Spain
| | - Julen Ibañez-Azpiroz
- Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, D-52425 Jülich, Germany
| | - Aitor Bergara
- Centro de Física de Materiales CFM, CSIC-UPV/EHU, Manuel Lardizabal Pasealekua 5, 20018 Donostia/San Sebastián, Basque Country, Spain
- Donostia International Physics Center (DIPC), Manuel Lardizabal Pasealekua 4, 20018 Donostia/San Sebastián, Basque Country, Spain
- Departamento de Física de la Materia Condensada, University of the Basque Country (UPV/EHU), 48080 Bilbao, Basque Country, Spain
| | - Ion Errea
- Donostia International Physics Center (DIPC), Manuel Lardizabal Pasealekua 4, 20018 Donostia/San Sebastián, Basque Country, Spain
- Fisika Aplikatua 1 Saila, Bilboko Ingeniaritza Eskola, University of the Basque Country (UPV/EHU), Rafael Moreno "Pitxitxi" Pasealekua 3, 48013 Bilbao, Basque Country, Spain
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27
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Nuclear quantum effects induce metallization of dense solid molecular hydrogen. J Comput Chem 2017; 39:262-268. [DOI: 10.1002/jcc.25104] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 10/19/2017] [Accepted: 10/23/2017] [Indexed: 01/21/2023]
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28
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Azadi S, Kühne TD. High-pressure hydrogen sulfide by diffusion quantum Monte Carlo. J Chem Phys 2017; 146:084503. [DOI: 10.1063/1.4976836] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Sam Azadi
- Department of Materials Science, Royal School of Mines, Thomas Young Center, London Centre for Nanotechnology, Imperial College London, London SW7 2AZ, United Kingdom
| | - Thomas D. Kühne
- Dynamics of Condensed Matter, Department of Chemistry, University of Paderborn, Warburger Strasse 100, D-33098 Paderborn, Germany and Paderborn Center for Parallel Computing and Institute for Lightweight Design with Hybrid Systems, University of Paderborn, Warburger Strasse 100, D-33098 Paderborn, Germany
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29
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Dias RP, Silvera IF. Observation of the Wigner-Huntington transition to metallic hydrogen. Science 2017; 355:715-718. [DOI: 10.1126/science.aal1579] [Citation(s) in RCA: 357] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 01/13/2017] [Indexed: 11/02/2022]
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30
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Azadi S, Ackland GJ. The role of van der Waals and exchange interactions in high-pressure solid hydrogen. Phys Chem Chem Phys 2017; 19:21829-21839. [DOI: 10.1039/c7cp03729e] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Our study of the van der Waals interactions in solid molecular hydrogen structures indicates two candidates for phase III.
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Affiliation(s)
- Sam Azadi
- Royal School of Mines and the Thomas Young Centre
- Imperial College London
- SW7 2AZ London
- UK
- School of Physics and Centre for Science at Extreme Conditions
| | - Graeme J. Ackland
- School of Physics and Centre for Science at Extreme Conditions
- University of Edinburgh
- Edinburgh EH9 3JZ
- UK
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31
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Borinaga M, Riego P, Leonardo A, Calandra M, Mauri F, Bergara A, Errea I. Anharmonic enhancement of superconductivity in metallic molecular Cmca - 4 hydrogen at high pressure: a first-principles study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:494001. [PMID: 27713189 DOI: 10.1088/0953-8984/28/49/494001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
First-principles calculations based on density-functional theory including anharmonicity within the variational stochastic self-consistent harmonic approximation are applied to understand how the quantum character of the proton affects the candidate metallic molecular Cmca - 4 structure of hydrogen in the 400-450 GPa pressure range, where metallization of hydrogen is expected to occur. Anharmonic effects, which become crucial due to the zero-point motion, have a large impact on the hydrogen molecules by increasing the intramolecular distance by approximately a 6%. This induces two new electron pockets at the Fermi surface opening new scattering channels for the electron-phonon interaction. Consequently, the electron-phonon coupling constant and the superconducting critical temperature are approximately doubled by anharmonicity and Cmca - 4 hydrogen becomes a superconductor above 200 K in all the studied pressure range. Contrary to many superconducting hydrides, where anharmoncity tends to lower the superconducting critical temperature, our results show that it can enhance superconductivity in molecular hydrogen.
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Affiliation(s)
- Miguel Borinaga
- Centro de Física de Materiales CFM, CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, 20018 Donostia/San Sebastián, Basque Country, Spain. Donostia International Physics Center (DIPC), Manuel Lardizabal pasealekua 4, 20018 Donostia/San Sebastián, Basque Country, Spain
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32
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Naumov II, Hemley RJ. Topological Surface States in Dense Solid Hydrogen. PHYSICAL REVIEW LETTERS 2016; 117:206403. [PMID: 27886502 DOI: 10.1103/physrevlett.117.206403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Indexed: 06/06/2023]
Abstract
Metallization of dense hydrogen and associated possible high-temperature superconductivity represents one of the key problems of physics. Recent theoretical studies indicate that before becoming a good metal, compressed solid hydrogen passes through a semimetallic stage. We show that such semimetallic phases predicted to be the most stable at multimegabar (∼300 GPa) pressures are not conventional semimetals: they exhibit topological metallic surface states inside the bulk "direct" gap in the two-dimensional surface Brillouin zone; that is, metallic surfaces may appear even when the bulk of the material remains insulating. Examples include hydrogen in the Cmca-12 and Cmca-4 structures; Pbcn hydrogen also has metallic surface states but they are of a nontopological nature. The results provide predictions for future measurements, including probes of possible surface superconductivity in dense hydrogen.
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Affiliation(s)
- Ivan I Naumov
- Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 20015, USA
| | - Russell J Hemley
- Department of Civil and Environmental Engineering, The George Washington University, Washington, D.C. 20052, USA
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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Azadi S, Cohen RE. Low-pressure phase diagram of crystalline benzene from quantum Monte Carlo. J Chem Phys 2016. [DOI: 10.1063/1.4960434] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Azadi S, Cohen RE. Chemical accuracy from quantum Monte Carlo for the benzene dimer. J Chem Phys 2016; 143:104301. [PMID: 26374029 DOI: 10.1063/1.4930137] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report an accurate study of interactions between benzene molecules using variational quantum Monte Carlo (VMC) and diffusion quantum Monte Carlo (DMC) methods. We compare these results with density functional theory using different van der Waals functionals. In our quantum Monte Carlo (QMC) calculations, we use accurate correlated trial wave functions including three-body Jastrow factors and backflow transformations. We consider two benzene molecules in the parallel displaced geometry, and find that by highly optimizing the wave function and introducing more dynamical correlation into the wave function, we compute the weak chemical binding energy between aromatic rings accurately. We find optimal VMC and DMC binding energies of -2.3(4) and -2.7(3) kcal/mol, respectively. The best estimate of the coupled-cluster theory through perturbative triplets/complete basis set limit is -2.65(2) kcal/mol [Miliordos et al., J. Phys. Chem. A 118, 7568 (2014)]. Our results indicate that QMC methods give chemical accuracy for weakly bound van der Waals molecular interactions, comparable to results from the best quantum chemistry methods.
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Affiliation(s)
- Sam Azadi
- Department of Earth Science and Thomas Young Centre, University College London, London WC1E 6BT, United Kingdom
| | - R E Cohen
- London Centre for Nanotechnology, University College London, London WC1E 6BT, United Kingdom and Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 20015, USA
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Dalladay-Simpson P, Howie RT, Gregoryanz E. Evidence for a new phase of dense hydrogen above 325 gigapascals. Nature 2016; 529:63-7. [PMID: 26738591 DOI: 10.1038/nature16164] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 10/14/2015] [Indexed: 11/09/2022]
Abstract
Almost 80 years ago it was predicted that, under sufficient compression, the H-H bond in molecular hydrogen (H2) would break, forming a new, atomic, metallic, solid state of hydrogen. Reaching this predicted state experimentally has been one of the principal goals in high-pressure research for the past 30 years. Here, using in situ high-pressure Raman spectroscopy, we present evidence that at pressures greater than 325 gigapascals at 300 kelvin, H2 and hydrogen deuteride (HD) transform to a new phase--phase V. This new phase of hydrogen is characterized by substantial weakening of the vibrational Raman activity, a change in pressure dependence of the fundamental vibrational frequency and partial loss of the low-frequency excitations. We map out the domain in pressure-temperature space of the suggested phase V in H2 and HD up to 388 gigapascals at 300 kelvin, and up to 465 kelvin at 350 gigapascals; we do not observe phase V in deuterium (D2). However, we show that the transformation to phase IV' in D2 occurs above 310 gigapascals and 300 kelvin. These values represent the largest known isotropic shift in pressure, and hence the largest possible pressure difference between the H2 and D2 phases, which implies that the appearance of phase V of D2 must occur at a pressure of above 380 gigapascals. These experimental data provide a glimpse of the physical properties of dense hydrogen above 325 gigapascals and constrain the pressure and temperature conditions at which the new phase exists. We speculate that phase V may be the precursor to the non-molecular (atomic and metallic) state of hydrogen that was predicted 80 years ago.
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Affiliation(s)
- Philip Dalladay-Simpson
- School of Physics and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3JZ, UK
| | - Ross T Howie
- School of Physics and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3JZ, UK
| | - Eugene Gregoryanz
- School of Physics and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3JZ, UK.,Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
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Azadi S, Foulkes WMC. Systematic study of finite-size effects in quantum Monte Carlo calculations of real metallic systems. J Chem Phys 2015; 143:102807. [DOI: 10.1063/1.4922619] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Affiliation(s)
- Sam Azadi
- Department of Physics, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - W. M. C. Foulkes
- Department of Physics, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
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Drummond ND, Monserrat B, Lloyd-Williams JH, Ríos PL, Pickard CJ, Needs RJ. Quantum Monte Carlo study of the phase diagram of solid molecular hydrogen at extreme pressures. Nat Commun 2015; 6:7794. [PMID: 26215251 PMCID: PMC4525154 DOI: 10.1038/ncomms8794] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 06/10/2015] [Indexed: 11/08/2022] Open
Abstract
Establishing the phase diagram of hydrogen is a major challenge for experimental and theoretical physics. Experiment alone cannot establish the atomic structure of solid hydrogen at high pressure, because hydrogen scatters X-rays only weakly. Instead, our understanding of the atomic structure is largely based on density functional theory (DFT). By comparing Raman spectra for low-energy structures found in DFT searches with experimental spectra, candidate atomic structures have been identified for each experimentally observed phase. Unfortunately, DFT predicts a metallic structure to be energetically favoured at a broad range of pressures up to 400 GPa, where it is known experimentally that hydrogen is non-metallic. Here we show that more advanced theoretical methods (diffusion quantum Monte Carlo calculations) find the metallic structure to be uncompetitive, and predict a phase diagram in reasonable agreement with experiment. This greatly strengthens the claim that the candidate atomic structures accurately model the experimentally observed phases.
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Affiliation(s)
- N. D. Drummond
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
| | - Bartomeu Monserrat
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - Jonathan H. Lloyd-Williams
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - P. López Ríos
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - Chris J. Pickard
- Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK
| | - R. J. Needs
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
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Tubman NM, Liberatore E, Pierleoni C, Holzmann M, Ceperley DM. Molecular-Atomic Transition along the Deuterium Hugoniot Curve with Coupled Electron-Ion Monte Carlo Simulations. PHYSICAL REVIEW LETTERS 2015; 115:045301. [PMID: 26252690 DOI: 10.1103/physrevlett.115.045301] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Indexed: 06/04/2023]
Abstract
We have performed simulations of the principal deuterium Hugoniot curve using coupled electron-ion Monte Carlo calculations. Using highly accurate quantum Monte Carlo methods for the electrons, we study the region of maximum compression along the Hugoniot, where the system undergoes a continuous transition from a molecular fluid to a monatomic fluid. We include all relevant physical corrections so that a direct comparison to experiment can be made. Around 50 GPa we find a maximum compression of 4.85. This compression is approximately 5.5% higher than previous theoretical predictions and 15% higher than the most accurate experimental data. Thus first-principles simulations encompassing the most advanced techniques are in disagreement with the results of the best experiments.
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Affiliation(s)
- Norm M Tubman
- Department of Physics, University of Illinois, Urbana, Illinois 61801, USA
| | | | - Carlo Pierleoni
- Department of Physical and Chemical Sciences, University of L'Aquila and CNISM UdR L'Aquila, Via Vetoio 10, I-67010 L'Aquila, Italy
| | - Markus Holzmann
- LPTMC, Université Pierre et Marie Curie and CNRS, 75005 Paris, France and LPMMC, Université Grenoble I and CNRS, 38042 Grenoble, France
| | - David M Ceperley
- Department of Physics, University of Illinois, Urbana, Illinois 61801, USA
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Ackland GJ, Magdău IB. Appraisal of the realistic accuracy of molecular dynamics of high-pressure hydrogen. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/23311940.2015.1049477] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Graeme J. Ackland
- CSEC, SUPA, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, EH9 3JZ, UK
| | - Ioan B. Magdău
- CSEC, SUPA, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, EH9 3JZ, UK
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McMinis J, Clay RC, Lee D, Morales MA. Molecular to atomic phase transition in hydrogen under high pressure. PHYSICAL REVIEW LETTERS 2015; 114:105305. [PMID: 25815944 DOI: 10.1103/physrevlett.114.105305] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Indexed: 06/04/2023]
Abstract
The metallization of high-pressure hydrogen, together with the associated molecular to atomic transition, is one of the most important problems in the field of high-pressure physics. It is also currently a matter of intense debate due to the existence of conflicting experimental reports on the observation of metallic hydrogen on a diamond-anvil cell. Theoretical calculations have typically relied on a mean-field description of electronic correlation through density functional theory, a theory with well-known limitations in the description of metal-insulator transitions. In fact, the predictions of the pressure-driven dissociation of molecules in high-pressure hydrogen by density functional theory is strongly affected by the chosen exchange-correlation functional. In this Letter, we use quantum Monte Carlo calculations to study the molecular to atomic transition in hydrogen. We obtain a transition pressure of 447(3) GPa, in excellent agreement with the best experimental estimate of the transition 450 GPa based on an extrapolation to zero band gap from experimental measurements. Additionally, we find that C2/c is stable almost up to the molecular to atomic transition, in contrast to previous density functional theory (DFT) and DFT+quantum Monte Carlo studies which predict large stability regimes for intermediary molecular phases.
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Affiliation(s)
- Jeremy McMinis
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Raymond C Clay
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
- University of Illinois, Urbana, Illinois 61821, USA
| | - Donghwa Lee
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Miguel A Morales
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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Monserrat B, Needs RJ, Pickard CJ. Temperature effects in first-principles solid state calculations of the chemical shielding tensor made simple. J Chem Phys 2014; 141:134113. [DOI: 10.1063/1.4897261] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Bartomeu Monserrat
- TCM Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Richard J. Needs
- TCM Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Chris J. Pickard
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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