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Zhang S, Yang Q, Zhang X, Zhao K, Yu H, Zhu L, Liu H. Crystal structures and superconductivity of lithium and fluorine implanted gold hydrides under high pressures. Phys Chem Chem Phys 2021; 23:21544-21553. [PMID: 34549743 DOI: 10.1039/d1cp02781f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The investigations on gold science have been capturing research interest due to its diverse physical and chemical properties. Gold hydrides in the solid state, as a member of the Au compound family, are rare since the reaction of Au with H is hindered in terms of their similar electronegativity. It is expected that Li and F can provide electrons and holes, respectively, to help stabilize gold hydrides under high pressure. Herein, by means of a crystal structural search based on particle swarm optimization methodology accompanied by first-principles calculations, four hitherto unknown Li-Au-H compounds (i.e., LiAuH, LiAu2H, Li2Au2H, and Li6AuH) are predicted to be stable under compression. Intriguingly, Au-H bonding is found in LiAuH, LiAu2H, and Li2Au2H. As the gold content increases, Au atom arrangements exhibit diverse forms, from the chain in Li6AuH, the square layer in LiAuH, the network in Li2Au2H, and eventually to the coexistence of square and pyramid layers in LiAu2H. Additionally, Li6AuH has a unique cage-type lithium structure. Furthermore, electron-phonon coupling calculations show that these Li-Au-H phases are phonon-modulated superconductors with a superconducting critical temperature of 1.3, 0.06, and 0.02 K at 25 GPa and 2.79 K at 100 GPa. In contrast, we also identified two solid F4AuH and F6AuH phases with unexpected semiconductivity. They have structural configurations of H-bridged AuF4 quasi-square components and distorted AuF6 octahedrons, respectively, and have no gold-to-hydrogen bonds. Our current results indicate that electron doping at suitable concentrations under pressure can stabilize unique gold hydrides, and provide deep insights into the structures, electron properties, bonding behavior, and stability mechanism of ternary Li-Au-H and F-Au-H compounds.
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Affiliation(s)
- Shoutao Zhang
- Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, China.
| | - Qiuping Yang
- Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, China.
| | - Xiaohua Zhang
- Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, China.
| | - Kaixuan Zhao
- Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, China.
| | - Hong Yu
- Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, China.
| | - Li Zhu
- Department of Physics, Rutgers University, Newark, NJ 07102, USA.
| | - Hanyu Liu
- International Center for Computational Method & Software and State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China. .,Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education),College of Physics, Jilin University, Changchun 130012, China
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2
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Tse JS. A chemical perspective on high pressure crystal structures and properties. Natl Sci Rev 2020; 7:149-169. [PMID: 34692029 PMCID: PMC8289026 DOI: 10.1093/nsr/nwz144] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 07/25/2019] [Accepted: 08/20/2019] [Indexed: 11/13/2022] Open
Abstract
The general availability of third generation synchrotron sources has ushered in a new era of high pressure research. The crystal structure of materials under compression can now be determined by X-ray diffraction using powder samples and, more recently, from multi-nano single crystal diffraction. Concurrently, these experimental advancements are accompanied by a rapid increase in computational capacity and capability, enabling the application of sophisticated quantum calculations to explore a variety of material properties. One of the early surprises is the finding that simple metallic elements do not conform to the general expectation of adopting 3D close-pack structures at high pressure. Instead, many novel open structures have been identified with no known analogues at ambient pressure. The occurrence of these structural types appears to be random with no rules governing their formation. The adoption of an open structure at high pressure suggested the presence of directional bonds. Therefore, a localized atomic hybrid orbital description of the chemical bonding may be appropriate. Here, the theoretical foundation and experimental evidence supporting this approach to the elucidation of the high pressure crystal structures of group I and II elements and polyhydrides are reviewed. It is desirable and advantageous to extend and apply established chemical principles to the study of the chemistry and chemical bonding of materials at high pressure.
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Affiliation(s)
- John S Tse
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
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Rahm M, Cammi R, Ashcroft NW, Hoffmann R. Squeezing All Elements in the Periodic Table: Electron Configuration and Electronegativity of the Atoms under Compression. J Am Chem Soc 2019; 141:10253-10271. [PMID: 31144505 DOI: 10.1021/jacs.9b02634] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present a quantum mechanical model capable of describing isotropic compression of single atoms in a non-reactive neon-like environment. Studies of 93 atoms predict drastic changes to ground-state electronic configurations and electronegativity in the pressure range of 0-300 GPa. This extension of atomic reference data assists in the working of chemical intuition at extreme pressure and can act as a guide to both experiments and computational efforts. For example, we can speculate on the existence of pressure-induced polarity (red-ox) inversions in various alloys. Our study confirms that the filling of energy levels in compressed atoms more closely follows the hydrogenic aufbau principle, where the ordering is determined by the principal quantum number. In contrast, the Madelung energy ordering rule is not predictive for atoms under compression. Magnetism may increase or decrease with pressure, depending on which atom is considered. However, Hund's rule is never violated for single atoms in the considered pressure range. Important (and understandable) electron shifts, s→p, s→d, s→f, and d→f are essential chemical and physical consequences of compression. Among the specific intriguing changes predicted are an increase in the range between the most and least electronegative elements with compression; a rearrangement of electronegativities of the alkali metals with pressure, with Na becoming the most electropositive s1 element (while Li becomes a p group element and K and heavier become transition metals); phase transitions in Ca, Sr, and Ba correlating well with s→d transitions; spin-reduction in all d-block atoms for which the valence d-shell occupation is d n (4 ≤ n ≤ 8); d→f transitions in Ce, Dy, and Cm causing Ce to become the most electropositive element of the f-block; f→d transitions in Ho, Dy, and Tb and a s→f transition in Pu. At high pressure Sc and Ti become the most electropositive elements, while Ne, He, and F remain the most electronegative ones.
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Affiliation(s)
- Martin Rahm
- Department of Chemistry and Chemical Engineering , Chalmers University of Technology , SE-412 96 Gothenburg , Sweden
| | - Roberto Cammi
- Department of Chemical Science, Life Science and Environmental Sustainability , University of Parma , 43124 Parma , Italy
| | - N W Ashcroft
- Laboratory of Atomic and Solid State Physics , Cornell University , Ithaca , New York 14853 , United States
| | - Roald Hoffmann
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
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Zhang Y, Wu W, Wang Y, Yang SA, Ma Y. Pressure-Stabilized Semiconducting Electrides in Alkaline-Earth-Metal Subnitrides. J Am Chem Soc 2017; 139:13798-13803. [DOI: 10.1021/jacs.7b07016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yunwei Zhang
- State
Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- Beijing Computational Science Research Center, Beijing 100084, China
- Research
Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Weikang Wu
- Research
Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Yanchao Wang
- State
Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Shengyuan A. Yang
- Research
Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Yanming Ma
- State
Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- International
Center of Future Science, Jilin University, Changchun 130012, China
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5
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Naumov II, Hemley RJ, Hoffmann R, Ashcroft NW. Chemical bonding in hydrogen and lithium under pressure. J Chem Phys 2015; 143:064702. [PMID: 26277151 DOI: 10.1063/1.4928076] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Though hydrogen and lithium have been assigned a common column of the periodic table, their crystalline states under common conditions are drastically different: the former at temperatures where it is crystalline is a molecular insulator, whereas the latter is a metal that takes on simple structures. On compression, however, the two come to share some structural and other similarities associated with the insulator-to-metal and metal-to-insulator transitions, respectively. To gain a deeper understanding of differences and parallels in the behaviors of compressed hydrogen and lithium, we performed an ab initio comparative study of these systems in selected identical structures. Both elements undergo a continuous pressure-induced s-p electronic transition, though this is at a much earlier stage of development for H. The valence charge density accumulates in interstitial regions in Li but not in H in structures examined over the same range of compression. Moreover, the valence charge density distributions or electron localization functions for the same arrangement of atoms mirror each other as one proceeds from one element to the other. Application of the virial theorem shows that the kinetic and potential energies jump across the first-order phase transitions in H and Li are opposite in sign because of non-local effects in the Li pseudopotential. Finally, the common tendency of compressed H and Li to adopt three-fold coordinated structures as found is explained by the fact that such structures are capable of yielding a profound pseudogap in the electronic densities of states at the Fermi level, thereby reducing the kinetic energy. These results have implications for the phase diagrams of these elements and also for the search for new structures with novel properties.
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Affiliation(s)
- Ivan I Naumov
- Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC 20015, USA
| | - Russell J Hemley
- Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC 20015, USA
| | - Roald Hoffmann
- Baker Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - N W Ashcroft
- Laboratory of Atomic and Solid State Physics and Cornell Center for Materials Research, Cornell University, Clark Hall, Ithaca, New York 14853, USA
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Wang Y, Lv J, Zhu L, Lu S, Yin K, Li Q, Wang H, Zhang L, Ma Y. Materials discovery via CALYPSO methodology. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:203203. [PMID: 25921406 DOI: 10.1088/0953-8984/27/20/203203] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The structure prediction at the atomic level is emerging as a state-of-the-art approach to accelerate the functionality-driven discovery of materials. By combining the global swarm optimization algorithm with first-principles thermodynamic calculations, it exploits the power of current supercomputer architectures to robustly predict the ground state and metastable structures of materials with only the given knowledge of chemical composition. In this Review, we provide an overview of the basic theory and main features of our as-developed CALYPSO structure prediction method, as well as its versatile applications to design of a broad range of materials including those of three-dimensional bulks, two-dimensional reconstructed surfaces and layers, and isolated clusters/nanoparticles or molecules with a variety of functional properties. The current challenges faced by structure prediction for materials discovery and future developments of CALYPSO to overcome them are also discussed.
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Affiliation(s)
- Yanchao Wang
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China. College of Materials Science and Engineering, Jilin University, Changchun 130012, People's Republic of China
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Abstract
Crystal structure prediction at high pressures unbiased by any prior known structure information has recently become a topic of considerable interest. We here present a short overview of recently developed structure prediction methods and propose current challenges for crystal structure prediction. We focus on first-principles crystal structure prediction at high pressures, paying particular attention to novel high pressure structures uncovered by efficient structure prediction methods. Finally, a brief perspective on the outstanding issues that remain to be solved and some directions for future structure prediction researches at high pressure are presented and discussed.
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Affiliation(s)
- Yanchao Wang
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China
| | - Yanming Ma
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China
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Naumov II, Hemley RJ. Origin of Transitions between Metallic and Insulating States in Simple Metals. PHYSICAL REVIEW LETTERS 2015; 114:156403. [PMID: 25933325 DOI: 10.1103/physrevlett.114.156403] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Indexed: 06/04/2023]
Abstract
Unifying principles that underlie recently discovered transitions between metallic and insulating states in elemental solids under pressure are developed. Using group theory arguments and first-principles calculations, we show that the electronic properties of the phases involved in these transitions are controlled by symmetry principles. The valence bands in these systems are described by simple and composite band representations constructed from localized Wannier functions centered on points unoccupied by atoms, and which are not necessarily all symmetrical. The character of the Wannier functions is closely related to the degree of s-p(-d) hybridization and reflects multicenter chemical bonding in these insulating states. The conditions under which an insulating state is allowed for structures having an integer number of atoms per primitive unit cell as well as reentrant (i.e., metal-insulator-metal) transition sequences are detailed, resulting in predictions of behavior such as phases having band-contact lines. The general principles developed are tested and applied to the alkali and alkaline earth metals, including elements where high-pressure insulating phases have been reported (e.g., Li, Na, and Ca).
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Affiliation(s)
- Ivan I Naumov
- Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, D.C. 20015, USA
| | - Russell J Hemley
- Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, D.C. 20015, USA
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Miao MS, Hoffmann R. High-Pressure Electrides: The Chemical Nature of Interstitial Quasiatoms. J Am Chem Soc 2015; 137:3631-7. [DOI: 10.1021/jacs.5b00242] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Mao-sheng Miao
- Department
of Chemistry and Biochemistry, California State University, Northridge, California 91330, United States
- Beijing Computational Science Research Center, Beijing 10084, P. R. China
| | - Roald Hoffmann
- Department of Chemistry & Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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10
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Gorelli FA, Elatresh SF, Guillaume CL, Marqués M, Ackland GJ, Santoro M, Bonev SA, Gregoryanz E. Lattice dynamics of dense lithium. PHYSICAL REVIEW LETTERS 2012; 108:055501. [PMID: 22400938 DOI: 10.1103/physrevlett.108.055501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Indexed: 05/31/2023]
Abstract
We report low-frequency high-resolution Raman spectroscopy and ab-initio calculations on dense lithium from 40 to 200 GPa at low temperatures. Our experimental results reveal rich first-order Raman activity in the metallic and semiconducting phases of lithium. The computed Raman frequencies are in excellent agreement with the measurements. Free energy calculations provide a quantitative description and physical explanation of the experimental phase diagram only when vibrational effect are correctly treated. The study underlines the importance of zero-point energy in determining the phase stability of compressed lithium.
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Affiliation(s)
- F A Gorelli
- LENS, European Laboratory for Non-Linear Spectroscopy, University of Florence, I-50121 Florence, Italy
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11
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Marqués M, McMahon MI, Gregoryanz E, Hanfland M, Guillaume CL, Pickard CJ, Ackland GJ, Nelmes RJ. Crystal structures of dense lithium: a metal-semiconductor-metal transition. PHYSICAL REVIEW LETTERS 2011; 106:095502. [PMID: 21405633 DOI: 10.1103/physrevlett.106.095502] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Indexed: 05/30/2023]
Abstract
Ab initio random structure searching and single-crystal x-ray diffraction have been used to determine the full structures of three phases of lithium, recently discovered at low temperature above 60 GPa. A structure with C2mb symmetry, calculated to be a poor metal, is proposed for the oC88 phase (60-65 GPa). The oC40 phase (65-95 GPa) is found to have a lowest-enthalpy structure with C2cb symmetry, in excellent agreement with the x-ray data. It is calculated to be a semiconductor with a band gap of ∼1 eV at 90 GPa. oC24, stable above 95 GPa, has the space group Cmca, and refined atomic coordinates are in excellent agreement with previous calculations.
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Affiliation(s)
- M Marqués
- SUPA, School of Physics and Astronomy, Centre for Science at Extreme Conditions, The University of Edinburgh, United Kingdom
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12
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Pickard CJ, Needs RJ. Ab initio random structure searching. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:053201. [PMID: 21406903 DOI: 10.1088/0953-8984/23/5/053201] [Citation(s) in RCA: 349] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
It is essential to know the arrangement of the atoms in a material in order to compute and understand its properties. Searching for stable structures of materials using first-principles electronic structure methods, such as density-functional-theory (DFT), is a rapidly growing field. Here we describe our simple, elegant and powerful approach to searching for structures with DFT, which we call ab initio random structure searching (AIRSS). Applications to discovering the structures of solids, point defects, surfaces, and clusters are reviewed. New results for iron clusters on graphene, silicon clusters, polymeric nitrogen, hydrogen-rich lithium hydrides, and boron are presented.
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Affiliation(s)
- Chris J Pickard
- Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
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Lv J, Wang Y, Zhu L, Ma Y. Predicted novel high-pressure phases of lithium. PHYSICAL REVIEW LETTERS 2011; 106:015503. [PMID: 21231754 DOI: 10.1103/physrevlett.106.015503] [Citation(s) in RCA: 162] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Indexed: 05/30/2023]
Abstract
Under high pressure, "simple" lithium (Li) exhibits complex structural behavior, and even experiences an unusual metal-to-semiconductor transition, leading to topics of interest in the structural polymorphs of dense Li. We here report two unexpected orthorhombic high-pressure structures Aba2-40 (40 atoms/cell, stable at 60-80 GPa) and Cmca-56 (56 atoms/cell, stable at 185-269 GPa), by using a newly developed particle swarm optimization technique on crystal structure prediction. The Aba2-40 having complex 4- and 8-atom layers stacked along the b axis is a semiconductor with a pronounced band gap >0.8 eV at 70 GPa originating from the core expulsion and localization of valence electrons in the voids of a crystal. We predict that a local trigonal planar structural motif adopted by Cmca-56 exists in a wide pressure range of 85-434 GPa, favorable for the weak metallicity.
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Affiliation(s)
- Jian Lv
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China
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Yang J, Tse JS, Iitaka T. First-principles studies of liquid lithium under pressure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:095503. [PMID: 21389418 DOI: 10.1088/0953-8984/22/9/095503] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Effects of compression on the structural and electronic properties of liquid lithium are investigated with first-principles molecular dynamics calculations. Within a large pressure range up to 60 GPa, along isotherms from 600 to 1000 K, several structural transformations were found. The liquid structures at high pressure are found to be not sensitive to the temperature within this range. It is shown that the radial distribution functions broadly resemble the corresponding solid phases, particularly at low pressures. The evolution of the electronic structure under pressure also shows a remarkable similarity to the underlying solid. However, detailed analyses of the temporal liquid inherent structures show that the instantaneous short-range order may differ significantly from the underlying known solid phase.
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Affiliation(s)
- Jianjun Yang
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada
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Pickard CJ, Needs RJ. Dense low-coordination phases of lithium. PHYSICAL REVIEW LETTERS 2009; 102:146401. [PMID: 19392459 DOI: 10.1103/physrevlett.102.146401] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Indexed: 05/27/2023]
Abstract
Ab initio density-functional-theory calculations and a structure-searching technique are used to identify candidate high-pressure phases of lithium (Li). We predict threefold coordinated structures to be stable in the pressure range 40-450 GPa and fourfold structures at higher pressures. We describe these low-coordination phases as elemental electrides. All of the stable phases are metallic but the Cmca-24 structure, and two distortions of it which are marginally the most stable in the pressure range 86-106 GPa, are nearly semiconducting with densities of electronic states at the Fermi energy of only a few percent of the free-electron value.
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Affiliation(s)
- Chris J Pickard
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St. Andrews, St Andrews, KY16 9SS, United Kingdom
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16
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Yao Y, Tse JS, Klug DD. Structures of insulating phases of dense lithium. PHYSICAL REVIEW LETTERS 2009; 102:115503. [PMID: 19392214 DOI: 10.1103/physrevlett.102.115503] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2008] [Indexed: 05/27/2023]
Abstract
Two high-pressure insulating phases of lithium were predicted using random search and evolutionary algorithm methods with first-principles electronic structure calculations. It is shown that lithium will transform from the metallic cubic cI16 phase to an insulating monoclinic C2 structure at 74 GPa. The C2 structure is the most stable phase up to 91 GPa, where it transforms to a second insulating orthorhombic Aba2 structure. The C2 and Aba2 structures are the first theoretical models explicitly showing the band gap opening in compressed lithium. The theoretical findings are supported by recent experimental evidence from electrical resistance and x-ray diffraction measurements.
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Affiliation(s)
- Yansun Yao
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, Canada, K1A 0R6
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17
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Direct observation of a pressure-induced metal-to-semiconductor transition in lithium. Nature 2009; 458:186-9. [DOI: 10.1038/nature07827] [Citation(s) in RCA: 201] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Accepted: 01/19/2009] [Indexed: 11/08/2022]
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Tamblyn I, Raty JY, Bonev SA. Tetrahedral clustering in molten lithium under pressure. PHYSICAL REVIEW LETTERS 2008; 101:075703. [PMID: 18764552 DOI: 10.1103/physrevlett.101.075703] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2008] [Revised: 06/20/2008] [Indexed: 05/26/2023]
Abstract
A series of electronic and structural transitions are predicted in molten lithium from first principles. A new phase with tetrahedral local order characteristic of sp3 bonded materials and poor electrical conductivity is found at pressures above 150 GPa and temperatures as high as 1000 K. Despite the lack of covalent bonding, weakly bound tetrahedral clusters with finite lifetimes are predicted to exist. The stabilization of this phase in lithium involves a unique mechanism of strong electron localization in interstitial regions and interactions among core electrons. The calculations provide evidence for anomalous melting above 20 GPa, with a melting temperature decreasing below 300 K, and point towards the existence of novel low-symmetry crystalline phases.
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Affiliation(s)
- Isaac Tamblyn
- Department of Physics, Dalhousie University, Halifax, Nova Scotia, B3H 3J5, Canada
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Kietzmann A, Redmer R, Desjarlais MP, Mattsson TR. Complex behavior of fluid lithium under extreme conditions. PHYSICAL REVIEW LETTERS 2008; 101:070401. [PMID: 18764511 DOI: 10.1103/physrevlett.101.070401] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2008] [Indexed: 05/26/2023]
Abstract
Lithium is a prototypical simple metal at standard conditions which is well described within the nearly free electron model. However, by changing the density towards expanded or compressed states, the electrical conductivity shows strong and partly unexpected variations. We have performed quantum molecular dynamics simulations for fluid lithium for a wide range of densities and temperatures in order to derive the equation of state, the electrical conductivity, and information about structural and electronic changes along the expansion or compression. Based on these results, we can give a consistent description of the electrical conductivity from the nonmetallic expanded fluid up to the degenerate electron liquid at high densities.
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Affiliation(s)
- André Kietzmann
- Institut für Physik, Universität Rostock, D-18051 Rostock, Germany
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