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Wang X, Wang Z, Gao P, Zhang C, Lv J, Wang H, Liu H, Wang Y, Ma Y. Data-driven prediction of complex crystal structures of dense lithium. Nat Commun 2023; 14:2924. [PMID: 37217498 DOI: 10.1038/s41467-023-38650-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 05/09/2023] [Indexed: 05/24/2023] Open
Abstract
Lithium (Li) is a prototypical simple metal at ambient conditions, but exhibits remarkable changes in structural and electronic properties under compression. There has been intense debate about the structure of dense Li, and recent experiments offered fresh evidence for yet undetermined crystalline phases near the enigmatic melting minimum region in the pressure-temperature phase diagram of Li. Here, we report on an extensive exploration of the energy landscape of Li using an advanced crystal structure search method combined with a machine-learning approach, which greatly expands the scale of structure search, leading to the prediction of four complex Li crystal structures containing up to 192 atoms in the unit cell that are energetically competitive with known Li structures. These findings provide a viable solution to the observed yet unidentified crystalline phases of Li, and showcase the predictive power of the global structure search method for discovering complex crystal structures in conjunction with accurate machine learning potentials.
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Affiliation(s)
- Xiaoyang Wang
- Key Laboratory of Material Simulation Methods & Software of Ministry of Education and State Key Laboratory of Superhard Materials, College of Physics, Jilin University, 130012, Changchun, People's Republic of China
- Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Fenghao East Road 2, 100094, Beijing, People's Republic of China
| | - Zhenyu Wang
- Key Laboratory of Material Simulation Methods & Software of Ministry of Education and State Key Laboratory of Superhard Materials, College of Physics, Jilin University, 130012, Changchun, People's Republic of China
| | - Pengyue Gao
- Key Laboratory of Material Simulation Methods & Software of Ministry of Education and State Key Laboratory of Superhard Materials, College of Physics, Jilin University, 130012, Changchun, People's Republic of China
| | - Chengqian Zhang
- DP Technology, 100080, Beijing, People's Republic of China
- College of Engineering, Peking University, 100871, Beijing, People's Republic of China
| | - Jian Lv
- Key Laboratory of Material Simulation Methods & Software of Ministry of Education and State Key Laboratory of Superhard Materials, College of Physics, Jilin University, 130012, Changchun, People's Republic of China.
| | - Han Wang
- Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Fenghao East Road 2, 100094, Beijing, People's Republic of China.
- HEDPS, CAPT, College of Engineering, Peking University, 100871, Beijing, People's Republic of China.
| | - Haifeng Liu
- Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Fenghao East Road 2, 100094, Beijing, People's Republic of China
| | - Yanchao Wang
- Key Laboratory of Material Simulation Methods & Software of Ministry of Education and State Key Laboratory of Superhard Materials, College of Physics, Jilin University, 130012, Changchun, People's Republic of China
| | - Yanming Ma
- Key Laboratory of Material Simulation Methods & Software of Ministry of Education and State Key Laboratory of Superhard Materials, College of Physics, Jilin University, 130012, Changchun, People's Republic of China.
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2
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Zheng Y, Jiang X, Xue XX, Yao X, Zeng J, Chen KQ, Wang E, Feng Y. Nuclear Quantum Effects on the Charge-Density Wave Transition in NbX 2 (X = S, Se). NANO LETTERS 2022; 22:1858-1865. [PMID: 35174707 DOI: 10.1021/acs.nanolett.1c04015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Understanding the origin of charge-density wave (CDW) instability is important for manipulating novel collective electronic states. Many layered transition metal dichalcogenides (TMDs) share similarity in the structural and electronic instability, giving rise to diverse CDW phases and superconductivity. It is still puzzling that even isostructural and isoelectronic TMDs show distinct CDW features. For instance, bulk NbSe2 exhibits CDW order at low temperature, while bulk NbS2 displays no CDW instability. The CDW transitions in single-layer NbS2 and NbSe2 are also different. In the classic limit, we investigate the electron correlation effects on the dimensionality dependence of the CDW ordering. By performing ab initio path integral molecular dynamics simulations and comparative analyses, we further revealed significant nuclear quantum effects in these systems. Specifically, the quantum motion of sulfur anions significantly reduces the CDW transition temperature in both bulk and single-layer NbS2, resulting in distinct CDW features in the NbS2 and NbSe2 systems.
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Affiliation(s)
- Yueshao Zheng
- School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China
| | - Xingxing Jiang
- School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China
| | - Xiong-Xiong Xue
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan 411105, People's Republic of China
| | - Xiaolong Yao
- School of Physics and Technology, Xinjiang University, Urumqi 830046, People's Republic of China
| | - Jiang Zeng
- School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China
| | - Ke-Qiu Chen
- School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China
| | - Enge Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Songshan Lake Materials, Institute of Physics, CAS and School of Physics, Liaoning University, Shenyang 110036, People's Republic of China
| | - Yexin Feng
- School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China
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3
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Chen Y, Yan X, Geng H, Sheng X, Zhang L, Wang H, Li J, Cao Y, Pan X. Prediction of Stable Ground-State Binary Sodium-Potassium Interalkalis under High Pressures. Inorg Chem 2021; 60:124-129. [PMID: 33352043 DOI: 10.1021/acs.inorgchem.0c02506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The complex structures and electronic properties of alkali metals and their alloys provide a natural laboratory for studying the interelectronic interactions of metals under compression. A recent theoretical study (J. Phys. Chem. Lett. 2019, 10, 3006) predicted an interesting pressure-induced decomposition-recombination behavior of the Na2K compound over a pressure range of 10-500 GPa. However, a subsequent experiment (Phys. Rev. B 2020, 101, 224108) reported the formation of NaK rather than Na2K at pressures above 5.9 GPa. To address this discordance, we study the chemical stability of different stoichiometries of NaxK (x = 1/4, 1/3, 1/2, 2/3, 3/4, 4/3, 3/2, and 1-4) by an effective structure searching method combined with first-principles calculations. Na2K is calculated to be unstable at 5-35 GPa due to the decomposition reaction Na2K → NaK + Na, coinciding well with the experiment. NaK undergoes a combination-decomposition-recombination process accompanied by an opposite charge-transfer behavior between Na and K with pressure. Besides NaK, two hitherto unknown compounds NaK3 and Na3K2 are uncovered. NaK3 is a typical metallic alloy, while Na3K2 is an electride with strong interstitial electron localization.
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Affiliation(s)
- Yangmei Chen
- School of Science, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi, People's Republic of China
| | - Xiaozhen Yan
- School of Science, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi, People's Republic of China.,National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, CAEP, P.O. Box 919-102, Mianyang 621900, Sichuan, People's Republic of China
| | - Huayun Geng
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, CAEP, P.O. Box 919-102, Mianyang 621900, Sichuan, People's Republic of China
| | - Xiaowei Sheng
- Department of Physics, Anhui Normal University, Anhui 241000, Wuhu, People's Republic of China
| | - Leilei Zhang
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, CAEP, P.O. Box 919-102, Mianyang 621900, Sichuan, People's Republic of China
| | - Hao Wang
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, CAEP, P.O. Box 919-102, Mianyang 621900, Sichuan, People's Republic of China
| | - Jinglong Li
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, CAEP, P.O. Box 919-102, Mianyang 621900, Sichuan, People's Republic of China
| | - Ye Cao
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, CAEP, P.O. Box 919-102, Mianyang 621900, Sichuan, People's Republic of China
| | - Xiaolong Pan
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, CAEP, P.O. Box 919-102, Mianyang 621900, Sichuan, People's Republic of China
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4
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Yang L, Qu X, Zhong X, Wang D, Chen Y, Yang J, Lv J, Liu H. Decomposition and Recombination of Binary Interalkali Na 2K at High Pressures. J Phys Chem Lett 2019; 10:3006-3012. [PMID: 31117694 DOI: 10.1021/acs.jpclett.9b00882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Under compression, "'simple'" alkali metals and their alloys exhibit complex structural and electronic properties, leading to fundamental interest in their high-pressure behaviors. Here, the swarm-intelligence structure-searching method was employed to identify the high-pressure phases of binary interalkali Na2K, which has long been known to possess a MgZn2-Laves phase at ambient pressure, but the high-pressure behavior remains elusive. We uncovered four new structures over a pressure range of 10-500 GPa, although the compound was found to become unstable upon decomposition into Na and K from 37 to 273 GPa. In phases before decomposition, the electrons were gradually delocalized with an increase in pressure and there was charge transfer from K to Na, whereas in phases after recombination, the electrons were gradually localized into the interstitials of the crystals, showing the unexpected opposite trend of charge transfer from Na to K, remarkably, where K was found to exhibit an oxidation state beyond the -1 valence state. The results can improve our understanding of the interaction and evolution of s electrons under compression.
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Affiliation(s)
- Lihua Yang
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education , Jilin Normal University , Changchun 130103 , P. R. China
- College of Physics , Jilin Normal University , Siping 136000 , China
- National Demonstration Center for Experimental Physics Education , Jilin Normal University , Siping 136000 , China
| | - Xin Qu
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education , Jilin Normal University , Changchun 130103 , P. R. China
- College of Physics , Jilin Normal University , Siping 136000 , China
- National Demonstration Center for Experimental Physics Education , Jilin Normal University , Siping 136000 , China
| | - Xin Zhong
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education , Jilin Normal University , Changchun 130103 , P. R. China
- College of Physics , Jilin Normal University , Siping 136000 , China
- National Demonstration Center for Experimental Physics Education , Jilin Normal University , Siping 136000 , China
| | - Dandan Wang
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education , Jilin Normal University , Changchun 130103 , P. R. China
- College of Physics , Jilin Normal University , Siping 136000 , China
- National Demonstration Center for Experimental Physics Education , Jilin Normal University , Siping 136000 , China
| | - Yanli Chen
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education , Jilin Normal University , Changchun 130103 , P. R. China
- College of Physics , Jilin Normal University , Siping 136000 , China
- National Demonstration Center for Experimental Physics Education , Jilin Normal University , Siping 136000 , China
| | - Jinghai Yang
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education , Jilin Normal University , Changchun 130103 , P. R. China
| | - Jian Lv
- State Key Laboratory of Superhard Materials, College of Physics , Jilin University , Changchun 130012 , China
| | - Hanyu Liu
- State Key Laboratory of Superhard Materials, College of Physics , Jilin University , Changchun 130012 , China
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5
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Feng Y, Zhao Y, Zhou WK, Li Q, Saidi WA, Zhao Q, Li XZ. Proton Migration in Hybrid Lead Iodide Perovskites: From Classical Hopping to Deep Quantum Tunneling. J Phys Chem Lett 2018; 9:6536-6543. [PMID: 30358406 DOI: 10.1021/acs.jpclett.8b02929] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The organic-inorganic halide perovskites (OIHPs) have shown enormous potential for solar cells, while problems like the current-voltage hysteresis and the long-term instability have seriously hindered their applications. Ion migrations are believed to be relevant. But the atomistic details still remain unclear. Here we study the migrations of ions in CH3NH3PbI3 (MAPbI3) at varying temperatures ( T's), using combined experimental and first-principle theoretical methods. Classical hopping of the iodide ions is the main migration mechanism at moderate T's. Below ∼270 K, the kinetic constant for ionic migration still shows an Arrenhius dependency, but the much lower activation energy is attributed to the migration of H+. A gradual classical-to-quantum transition takes place between ∼140 and ∼80 K. Below ∼80 K, the kinetic constant becomes T-independent, suggesting that deep quantum tunneling of H+ takes over. This study gives direct experimental evidence for the migrations of H+s in MAPbI3 and confirms their quantum nature.
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Affiliation(s)
- Yexin Feng
- State Key Laboratory for Mesoscopic Physics and School of Physics , Peking University , Beijing 100871 , P. R. China
- School of Physics and Electronics , Hunan University , Changsha 410082 , P. R. China
| | - Yicheng Zhao
- State Key Laboratory for Mesoscopic Physics and School of Physics , Peking University , Beijing 100871 , P. R. China
| | - Wen-Ke Zhou
- State Key Laboratory for Mesoscopic Physics and School of Physics , Peking University , Beijing 100871 , P. R. China
| | - Qi Li
- State Key Laboratory for Mesoscopic Physics and School of Physics , Peking University , Beijing 100871 , P. R. China
| | - Wissam A Saidi
- Department of Mechanical Engineering and Materials Science , University of Pittsburgh , Pittsburgh , Pennsylvania 15261 , United States
| | - Qing Zhao
- State Key Laboratory for Mesoscopic Physics and School of Physics , Peking University , Beijing 100871 , P. R. China
- Collaborative Innovation Center of Quantum Matter , Peking University , Beijing 100871 , P. R. China
| | - Xin-Zheng Li
- State Key Laboratory for Mesoscopic Physics and School of Physics , Peking University , Beijing 100871 , P. R. China
- Collaborative Innovation Center of Quantum Matter , Peking University , Beijing 100871 , P. R. China
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6
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Poltavsky I, DiStasio RA, Tkatchenko A. Perturbed path integrals in imaginary time: Efficiently modeling nuclear quantum effects in molecules and materials. J Chem Phys 2018; 148:102325. [DOI: 10.1063/1.5006596] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Affiliation(s)
- Igor Poltavsky
- Physics and Materials Science Research Unit, University of Luxembourg, Luxembourg L-1511, Luxembourg
| | - Robert A. DiStasio
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Alexandre Tkatchenko
- Physics and Materials Science Research Unit, University of Luxembourg, Luxembourg L-1511, Luxembourg
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7
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Feng Y, Wang Z, Guo J, Chen J, Wang EG, Jiang Y, Li XZ. The collective and quantum nature of proton transfer in the cyclic water tetramer on NaCl(001). J Chem Phys 2018; 148:102329. [PMID: 29544296 DOI: 10.1063/1.5004737] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Proton tunneling is an elementary process in the dynamics of hydrogen-bonded systems. Collective tunneling is known to exist for a long time. Atomistic investigations of this mechanism in realistic systems, however, are scarce. Using a combination of ab initio theoretical and high-resolution experimental methods, we investigate the role played by the protons on the chirality switching of a water tetramer on NaCl(001). Our scanning tunneling spectroscopies show that partial deuteration of the H2O tetramer with only one D2O leads to a significant suppression of the chirality switching rate at a cryogenic temperature (T), indicating that the chirality switches by tunneling in a concerted manner. Theoretical simulations, in the meantime, support this picture by presenting a much smaller free-energy barrier for the translational collective proton tunneling mode than other chirality switching modes at low T. During this analysis, the virial energy provides a reasonable estimator for the description of the nuclear quantum effects when a traditional thermodynamic integration method cannot be used, which could be employed in future studies of similar problems. Given the high-dimensional nature of realistic systems and the topology of the hydrogen-bonded network, collective proton tunneling may exist more ubiquitously than expected. Systems of this kind can serve as ideal platforms for studies of this mechanism, easily accessible to high-resolution experimental measurements.
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Affiliation(s)
- Yexin Feng
- International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Zhichang Wang
- International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Jing Guo
- International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Ji Chen
- International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - En-Ge Wang
- International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Ying Jiang
- International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Xin-Zheng Li
- International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People's Republic of China
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8
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Karavaev AV, Dremov VV. A method of solid-solid phase equilibrium calculation by molecular dynamics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:495201. [PMID: 27754984 DOI: 10.1088/0953-8984/28/49/495201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A method for evaluation of solid-solid phase equilibrium curves in molecular dynamics simulation for a given model of interatomic interaction is proposed. The method allows to calculate entropies of crystal phases and provides an accuracy comparable with that of the thermodynamic integration method by Frenkel and Ladd while it is much simpler in realization and less intense computationally. The accuracy of the proposed method was demonstrated in MD calculations of entropies for EAM potential for iron and for MEAM potential for beryllium. The bcc-hcp equilibrium curves for iron calculated for the EAM potential by the thermodynamic integration method and by the proposed one agree quite well.
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Affiliation(s)
- A V Karavaev
- Russian Federal Nuclear Center-Zababakhin Institute of Technical Physics (RFNC-VNIITF), 13, Vasiliev st., Snezhinsk, Chelyabinsk reg. 456770, Russia
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9
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Geng HY, Wu Q. Predicted reentrant melting of dense hydrogen at ultra-high pressures. Sci Rep 2016; 6:36745. [PMID: 27834405 PMCID: PMC5105149 DOI: 10.1038/srep36745] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 10/20/2016] [Indexed: 01/28/2023] Open
Abstract
The phase diagram of hydrogen is one of the most important challenges in high-pressure physics and astrophysics. Especially, the melting of dense hydrogen is complicated by dimer dissociation, metallization and nuclear quantum effect of protons, which together lead to a cold melting of dense hydrogen when above 500 GPa. Nonetheless, the variation of the melting curve at higher pressures is virtually uncharted. Here we report that using ab initio molecular dynamics and path integral simulations based on density functional theory, a new atomic phase is discovered, which gives an uplifting melting curve of dense hydrogen when beyond 2 TPa, and results in a reentrant solid-liquid transition before entering the Wigner crystalline phase of protons. The findings greatly extend the phase diagram of dense hydrogen, and put metallic hydrogen into the group of alkali metals, with its melting curve closely resembling those of lithium and sodium.
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Affiliation(s)
- Hua Y. Geng
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, CAEP; P.O. Box 919-102, Mianyang, Sichuan, 621900, P. R. China
| | - Q. Wu
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, CAEP; P.O. Box 919-102, Mianyang, Sichuan, 621900, P. R. China
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10
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Guo J, Lü JT, Feng Y, Chen J, Peng J, Lin Z, Meng X, Wang Z, Li XZ, Wang EG, Jiang Y. Nuclear quantum effects of hydrogen bonds probed by tip-enhanced inelastic electron tunneling. Science 2016; 352:321-5. [PMID: 27081066 DOI: 10.1126/science.aaf2042] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/14/2016] [Indexed: 01/28/2023]
Abstract
We report the quantitative assessment of nuclear quantum effects on the strength of a single hydrogen bond formed at a water-salt interface, using tip-enhanced inelastic electron tunneling spectroscopy based on a scanning tunneling microscope. The inelastic scattering cross section was resonantly enhanced by "gating" the frontier orbitals of water via a chlorine-terminated tip, so the hydrogen-bonding strength can be determined with high accuracy from the red shift in the oxygen-hydrogen stretching frequency of water. Isotopic substitution experiments combined with quantum simulations reveal that the anharmonic quantum fluctuations of hydrogen nuclei weaken the weak hydrogen bonds and strengthen the relatively strong ones. However, this trend can be completely reversed when a hydrogen bond is strongly coupled to the polar atomic sites of the surface.
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Affiliation(s)
- Jing Guo
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
| | - Jing-Tao Lü
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Yexin Feng
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China. School of Physics and Electronics, Hunan University, Changsha 410082, P. R. China
| | - Ji Chen
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
| | - Jinbo Peng
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
| | - Zeren Lin
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
| | - Xiangzhi Meng
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
| | - Zhichang Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
| | - Xin-Zheng Li
- School of Physics, Peking University, Beijing 100871, P. R. China. Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China.
| | - En-Ge Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China. Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China.
| | - Ying Jiang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China. Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China.
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11
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Sun J, Clark BK, Torquato S, Car R. The phase diagram of high-pressure superionic ice. Nat Commun 2015; 6:8156. [PMID: 26315260 PMCID: PMC4560814 DOI: 10.1038/ncomms9156] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 07/26/2015] [Indexed: 11/12/2022] Open
Abstract
Superionic ice is a special group of ice phases at high temperature and pressure, which may exist in ice-rich planets and exoplanets. In superionic ice liquid hydrogen coexists with a crystalline oxygen sublattice. At high pressures, the properties of superionic ice are largely unknown. Here we report evidence that from 280 GPa to 1.3 TPa, there are several competing phases within the close-packed oxygen sublattice. At even higher pressure, the close-packed structure of the oxygen sublattice becomes unstable to a new unusual superionic phase in which the oxygen sublattice takes the P21/c symmetry. We also discover that higher pressure phases have lower transition temperatures. The diffusive hydrogen in the P21/c superionic phase shows strong anisotropic behaviour and forms a quasi-two-dimensional liquid. The ionic conductivity changes abruptly in the solid to close-packed superionic phase transition, but continuously in the solid to P21/c superionic phase transition. At high pressure, water forms superionic ice with an oxygen lattice and melted liquid hydrogens, which could exist on ice-rich planets. Here, Sun et al. predict a new phase of superionic ice where the hydrogens preferentially diffuse in two-dimensions within oxygen superlattice with the P21/c symmetry.
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Affiliation(s)
- Jiming Sun
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Bryan K Clark
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Salvatore Torquato
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.,Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.,Princeton Institute for the Science and Technology of Materials, Princeton, New Jersey 08544, USA
| | - Roberto Car
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.,Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.,Princeton Institute for the Science and Technology of Materials, Princeton, New Jersey 08544, USA
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12
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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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