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Shi J, Liang Z, Wang J, Pan S, Ding C, Wang Y, Wang HT, Xing D, Sun J. Double-Shock Compression Pathways from Diamond to BC8 Carbon. PHYSICAL REVIEW LETTERS 2023; 131:146101. [PMID: 37862650 DOI: 10.1103/physrevlett.131.146101] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/11/2023] [Accepted: 09/08/2023] [Indexed: 10/22/2023]
Abstract
Carbon is one of the most important elements for both industrial applications and fundamental research, including life, physics, chemistry, materials, and even planetary science. Although theoretical predictions on the transition from diamond to the BC8 (Ia3[over ¯]) carbon were made more than thirty years ago, after tremendous experimental efforts, direct evidence for the existence of BC8 carbon is still lacking. In this study, a machine learning potential was developed for high-pressure carbon fitted from first-principles calculations, which exhibited great capabilities in modeling the melting and Hugoniot line. Using the molecular dynamics based on this machine learning potential, we designed a thermodynamic pathway that is achievable for the double shock compression experiment to obtain the elusive BC8 carbon. Diamond was compressed up to 584 GPa after the first shock at 20.5 km/s. Subsequently, in the second shock compression at 24.8 or 25.0 km/s, diamond was compressed to a supercooled liquid and then solidified to BC8 in around 1 ns. Furthermore, the critical nucleus size and nucleation rate of BC8 were calculated, which are crucial for nano-second x-ray diffraction measurements to observe BC8 carbon during shock compressions. The key to obtaining BC8 carbon lies in the formation of liquid at a sufficient supercooling. Our work provides a feasible pathway by which the long-sought BC8 phase of carbon can be reached in experiments.
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Affiliation(s)
- Jiuyang Shi
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, People's Republic of China
| | - Zhixing Liang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, People's Republic of China
| | - Junjie Wang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, People's Republic of China
| | - Shuning Pan
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, People's Republic of China
| | - Chi Ding
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, People's Republic of China
| | - Yong Wang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, People's Republic of China
| | - Hui-Tian Wang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, People's Republic of China
| | - Dingyu Xing
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, People's Republic of China
| | - Jian Sun
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, People's Republic of China
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2
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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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3
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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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4
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Woodcox M, Young J, Smeu M. Ab initioinvestigation of the temperature-dependent elastic properties of Bi, Te and Cu. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:485902. [PMID: 32903220 DOI: 10.1088/1361-648x/ababdf] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/03/2020] [Indexed: 06/11/2023]
Abstract
Using density functional theory andab initiomolecular dynamics, we have investigated the elastic properties of Bi, Te and Cu as a function of temperature. We compare calculated quantities which can be used to determine the effectiveness of our proposed method, such as the bulk (K), shear (G), and Young's (E) moduli. We also computed Poisson's ratio (ν) and the Pugh ratio (γ) for each of these materials at different temperatures to investigate changes in ductility. We have used the elastic moduli to calculate the Debye temperatureθDand minimum thermal conductivitykminof these materials as a function of temperature. We found that the elastic properties calculated in this work are in good agreement with experimental work. The inclusion of temperature effects has allowed for the proper prediction of ductility for each of these materials, a feat that standard density functional theory calculations has previously been unable to accomplish for Bi and Te.
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Affiliation(s)
- Michael Woodcox
- Department of Physics, Binghamton University-SUNY, Binghamton, NY 13902, United States of America
| | - Joshua Young
- Department of Physics, Binghamton University-SUNY, Binghamton, NY 13902, United States of America
| | - Manuel Smeu
- Department of Physics, Binghamton University-SUNY, Binghamton, NY 13902, United States of America
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5
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Stability of H 3O at extreme conditions and implications for the magnetic fields of Uranus and Neptune. Proc Natl Acad Sci U S A 2020; 117:5638-5643. [PMID: 32127483 DOI: 10.1073/pnas.1921811117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The anomalous nondipolar and nonaxisymmetric magnetic fields of Uranus and Neptune have long challenged conventional views of planetary dynamos. A thin-shell dynamo conjecture captures the observed phenomena but leaves unexplained the fundamental material basis and underlying mechanism. Here we report extensive quantum-mechanical calculations of polymorphism in the hydrogen-oxygen system at the pressures and temperatures of the deep interiors of these ice giant planets (to >600 GPa and 7,000 K). The results reveal the surprising stability of solid and fluid trihydrogen oxide (H3O) at these extreme conditions. Fluid H3O is metallic and calculated to be stable near the cores of Uranus and Neptune. As a convecting fluid, the material could give rise to the magnetic field consistent with the thin-shell dynamo model proposed for these planets. H3O could also be a major component in both solid and superionic forms in other (e.g., nonconvecting) layers. The results thus provide a materials basis for understanding the enigmatic magnetic-field anomalies and other aspects of the interiors of Uranus and Neptune. These findings have direct implications for the internal structure, composition, and dynamos of related exoplanets.
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6
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Frost M, Kim JB, McBride EE, Peterson JR, Smith JS, Sun P, Glenzer SH. High-Pressure Melt Curve and Phase Diagram of Lithium. PHYSICAL REVIEW LETTERS 2019; 123:065701. [PMID: 31491150 DOI: 10.1103/physrevlett.123.065701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 06/11/2019] [Indexed: 06/10/2023]
Abstract
We investigate the phase diagram of lithium at temperatures of 200 to 400 K, to pressures over 100 GPa using x-ray diffraction in diamond anvil cells, covering the region in which the melting curve is disputed. To overcome degradation of the diamond anvils by dense lithium we utilize a rapid compression scheme taking advantage of the high flux available at modern synchrotrons. Our results show the hR1 and cI16 phases to be stable to higher temperature than previously reported. The melting minima of lithium is found to be close to room temperature between 40 and 60 GPa, below which the solid is crystalline. Analysis of the stability fields of the cI16 and oC88 phases suggest the existence of a triple point between these and an undetermined solid phase at 60 GPa between 220 and 255 K.
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Affiliation(s)
- Mungo Frost
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Jongjin B Kim
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Emma E McBride
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - J Ryan Peterson
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Physics Department, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA
| | - Jesse S Smith
- High Pressure Collaborative Access Team, X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Peihao Sun
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Physics Department, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA
| | - Siegfried H Glenzer
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
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7
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Dorner F, Sukurma Z, Dellago C, Kresse G. Melting Si: Beyond Density Functional Theory. PHYSICAL REVIEW LETTERS 2018; 121:195701. [PMID: 30468598 DOI: 10.1103/physrevlett.121.195701] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Indexed: 06/09/2023]
Abstract
The melting point of silicon in the cubic diamond phase is calculated using the random phase approximation (RPA). The RPA includes exact exchange as well as an approximate treatment of local as well as nonlocal many body correlation effects of the electrons. We predict a melting temperature of about 1735 and 1640 K without and with core polarization effects, respectively. Both values are within 3% of the experimental melting temperature of 1687 K. In comparison, the commonly used gradient approximation to density functional theory predicts a melting point that is 200 K too low, and hybrid functionals overestimate the melting point by 150 K. We correlate the predicted melting point with the energy difference between cubic diamond and the beta-tin phase of silicon, establishing that this energy difference is an important benchmark for the development of approximate functionals. The current results demonstrate that the RPA can be used to predict accurate finite temperature properties and underlines the excellent predictive properties of the RPA for condensed matter.
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Affiliation(s)
- Florian Dorner
- University of Vienna, Faculty of Physics and Center for Computational Materials Sciences, Sensengasse 8/12, 1090 Wien, Austria
| | - Zoran Sukurma
- University of Vienna, Faculty of Physics and Center for Computational Materials Sciences, Sensengasse 8/12, 1090 Wien, Austria
| | - Christoph Dellago
- University of Vienna, Faculty of Physics and Center for Computational Materials Sciences, Sensengasse 8/12, 1090 Wien, Austria
| | - Georg Kresse
- University of Vienna, Faculty of Physics and Center for Computational Materials Sciences, Sensengasse 8/12, 1090 Wien, Austria
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8
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Ackland GJ, Dunuwille M, Martinez-Canales M, Loa I, Zhang R, Sinogeikin S, Cai W, Deemyad S. Quantum and isotope effects in lithium metal. Science 2018. [PMID: 28642431 DOI: 10.1126/science.aal4886] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The crystal structure of elements at zero pressure and temperature is the most fundamental information in condensed matter physics. For decades it has been believed that lithium, the simplest metallic element, has a complicated ground-state crystal structure. Using synchrotron x-ray diffraction in diamond anvil cells and multiscale simulations with density functional theory and molecular dynamics, we show that the previously accepted martensitic ground state is metastable. The actual ground state is face-centered cubic (fcc). We find that isotopes of lithium, under similar thermal paths, exhibit a considerable difference in martensitic transition temperature. Lithium exhibits nuclear quantum mechanical effects, serving as a metallic intermediate between helium, with its quantum effect-dominated structures, and the higher-mass elements. By disentangling the quantum kinetic complexities, we prove that fcc lithium is the ground state, and we synthesize it by decompression.
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Affiliation(s)
- Graeme J Ackland
- Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, UK
| | - Mihindra Dunuwille
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Miguel Martinez-Canales
- Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, UK
| | - Ingo Loa
- Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, UK
| | - Rong Zhang
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Stanislav Sinogeikin
- High Pressure Collaborative Access Team (HPCAT), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, IL 60439, USA
| | - Weizhao Cai
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Shanti Deemyad
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA.
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9
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Meyer ER, Ticknor C, Kress JD, Collins LA. Alternative first-principles calculation of entropy for liquids. Phys Rev E 2016; 93:042119. [PMID: 27176266 DOI: 10.1103/physreve.93.042119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Indexed: 11/07/2022]
Abstract
We present an alternative method for interpreting the velocity autocorrelation function (VACF) of a fluid with application to extracting the entropy in a manner similar to the methods developed by Lin et al. [J. Chem. Phys. 119, 11792 (2003)]JCPSA60021-960610.1063/1.1624057 and improved upon by Desjarlais [Phys. Rev. E 88, 062145 (2013)]PLEEE81539-375510.1103/PhysRevE.88.062145. The liquid VACF is decomposed into two components, one gas and one solid, and each contribution's entropic portion is calculated. However, we fit both the gas and solid portions of the VACF in the time domain. This approach is applied to a single-component liquid (a two-phase model of liquid Al at the melt line) and two different two-component systems: a superionic-to-superionic (bcc to fcc) phase transition in H_{2}O at high temperatures and pressures and a metastable liquid state of MgO. For all three examples, comparisons to existing results in the literature demonstrate the validity of our alternative.
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Affiliation(s)
- Edmund R Meyer
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Christopher Ticknor
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Joel D Kress
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Lee A Collins
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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10
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Ab initio molecular dynamic study of solid-state transitions of ammonium nitrate. Sci Rep 2016; 6:18918. [PMID: 26754622 PMCID: PMC4709593 DOI: 10.1038/srep18918] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 11/30/2015] [Indexed: 11/09/2022] Open
Abstract
High-pressure polymorphism and phase transitions have wide ranging consequences on the basic properties of ammonium nitrate. However, the phase diagram of ammonium nitrate at high pressure and high temperature is still under debate. This study systematically investigates the phase transitions and structural properties of ammonium nitrate at a pressure range of 5-60 GPa and temperature range of 250-400 K by ab initio molecular dynamics simulations. Two new phases are identified: one corresponds to the experimentally observed phase IV' and the other is named AN-X. Simultaneously, the lattice strains play a significant role in the formation and stabilization of phase IV', providing a reasonable explanation for experimental observation of phase IV-IV' transition which only appears under nonhydrostatic pressure. In addition, 12 O atoms neighboring the NH (N atom in ammonium cation) atom are selected as reference system to clearly display the tanglesome rotation of ammonium cation.
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11
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Feng Y, Chen J, Alfè D, Li XZ, Wang E. Nuclear quantum effects on the high pressure melting of dense lithium. J Chem Phys 2015; 142:064506. [DOI: 10.1063/1.4907752] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Affiliation(s)
- Yexin Feng
- 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
| | - Dario Alfè
- London Centre for Nanotechnology, UCL, London WC1H 0AH, United Kingdom; Department of Physics and Astronomy, University College London, London WC1E6BT, United Kingdom; and Department of Earth Sciences, University College London, London WC1E6BT, United Kingdom
| | - Xin-Zheng Li
- International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People’s Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, People’s Republic of China
| | - Enge Wang
- International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People’s Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, People’s Republic of China
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12
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Vella JR, Stillinger FH, Panagiotopoulos AZ, Debenedetti PG. A Comparison of the Predictive Capabilities of the Embedded-Atom Method and Modified Embedded-Atom Method Potentials for Lithium. J Phys Chem B 2014; 119:8960-8. [DOI: 10.1021/jp5077752] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joseph R. Vella
- Department of Chemical and Biological
Engineering, and ‡Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Frank H. Stillinger
- Department of Chemical and Biological
Engineering, and ‡Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Athanassios Z. Panagiotopoulos
- Department of Chemical and Biological
Engineering, and ‡Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Pablo G. Debenedetti
- Department of Chemical and Biological
Engineering, and ‡Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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13
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Chen M, Hung L, Huang C, Xia J, Carter EA. The melting point of lithium: an orbital-free first-principles molecular dynamics study. Mol Phys 2013. [DOI: 10.1080/00268976.2013.828379] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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14
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Desjarlais MP. First-principles calculation of entropy for liquid metals. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:062145. [PMID: 24483423 DOI: 10.1103/physreve.88.062145] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Indexed: 06/03/2023]
Abstract
We demonstrate the accurate calculation of entropies and free energies for a variety of liquid metals using an extension of the two-phase thermodynamic (2PT) model based on a decomposition of the velocity autocorrelation function into gas-like (hard sphere) and solid-like (harmonic) subsystems. The hard sphere model for the gas-like component is shown to give systematically high entropies for liquid metals as a direct result of the unphysical Lorentzian high-frequency tail. Using a memory function framework we derive a generally applicable velocity autocorrelation and frequency spectrum for the diffusive component which recovers the low-frequency (long-time) behavior of the hard sphere model while providing for realistic short-time coherence and high-frequency tails to the spectrum. This approach provides a significant increase in the accuracy of the calculated entropies for liquid metals and is compared to ambient pressure data for liquid sodium, aluminum, gallium, tin, and iron. The use of this method for the determination of melt boundaries is demonstrated with a calculation of the high-pressure bcc melt boundary for sodium. With the significantly improved accuracy available with the memory function treatment for softer interatomic potentials, the 2PT model for entropy calculations should find broader application in high energy density science, warm dense matter, planetary science, geophysics, and material science.
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15
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Quantum simulation of low-temperature metallic liquid hydrogen. Nat Commun 2013; 4:2064. [DOI: 10.1038/ncomms3064] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 05/26/2013] [Indexed: 11/08/2022] Open
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16
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Wilson HF, Wong ML, Militzer B. Superionic to superionic phase change in water: consequences for the interiors of uranus and neptune. PHYSICAL REVIEW LETTERS 2013; 110:151102. [PMID: 25167242 DOI: 10.1103/physrevlett.110.151102] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 02/13/2013] [Indexed: 06/03/2023]
Abstract
Using density functional molecular dynamics free energy calculations, we show that the body centered cubic (bcc) phase of superionic ice previously believed to be the only phase is, in fact, thermodynamically unstable compared to a novel phase with oxygen positions in face centered cubic lattice sites. The novel phase has a lower proton mobility than the bcc phase and may exhibit a higher melting temperature. We predict a transition between the two phases at a pressure of 1±0.5 Mbar, with potential consequences for the interiors of ice giants such as Uranus and Neptune.
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Affiliation(s)
- Hugh F Wilson
- Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA
| | - Michael L Wong
- Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA
| | - Burkhard Militzer
- Department of Earth and Planetary Science and Department of Astronomy, University of California, Berkeley, California 94720, USA
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17
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Liu H, Ma Y. Proton or deuteron transfer in phase IV of solid hydrogen and deuterium. PHYSICAL REVIEW LETTERS 2013; 110:025903. [PMID: 23383917 DOI: 10.1103/physrevlett.110.025903] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Revised: 11/09/2012] [Indexed: 06/01/2023]
Abstract
The recent discovery of phase IV of solid hydrogen and deuterium consisting of two alternate layers of graphenelike three-molecule rings and unbound H2 molecules have generated great interest. However, the vibrational nature of phase IV remains poorly understood. Here, we report a peculiar proton or deuteron transfer and a simultaneous rotation of three-molecule rings in graphenelike layers predicted by ab initio variable-cell molecular dynamics simulations for phase IV of solid hydrogen and deuterium at pressure ranges of 250-350 GPa and temperature range of 300-500 K. This proton or deuteron transfer is intimately related to the particular elongation of molecules in graphenelike layers, and it becomes more pronounced with increasing pressure at the course of larger elongation of molecules. As the consequence of proton transfer, hydrogen molecules in graphenelike layers are short lived and hydrogen vibration is strongly anharmonic. Our findings provide direct explanations on the observed abrupt increase of Raman width at the formation of phase IV and its large increase with pressure.
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Affiliation(s)
- Hanyu Liu
- State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China
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Liu H, Zhu L, Cui W, Ma Y. Room-temperature structures of solid hydrogen at high pressures. J Chem Phys 2013; 137:074501. [PMID: 22920125 DOI: 10.1063/1.4745186] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
By employing first-principles metadynamics simulations, we explore the 300 K structures of solid hydrogen over the pressure range 150-300 GPa. At 200 GPa, we find the ambient-pressure disordered hexagonal close-packed (hcp) phase transited into an insulating partially ordered hcp phase (po-hcp), a mixture of ordered graphene-like H(2) layers and the other layers of weakly coupled, disordered H(2) molecules. Within this phase, hydrogen remains in paired states with creation of shorter intra-molecular bonds, which are responsible for the very high experimental Raman peak above 4000 cm(-1). At 275 GPa, our simulations predicted a transformation from po-hcp into the ordered molecular metallic Cmca phase (4 molecules/cell) that was previously proposed to be stable only above 400 GPa. Gibbs free energy calculations at 300 K confirmed the energetic stabilities of the po-hcp and metallic Cmca phases over all known structures at 220-242 GPa and >242 GPa, respectively. Our simulations highlighted the major role played by temperature in tuning the phase stabilities and provided theoretical support for claimed metallization of solid hydrogen below 300 GPa at 300 K.
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Affiliation(s)
- Hanyu Liu
- State Key Lab of Superhard Materials, Jilin University, Changchun 130012, China
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19
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Dozhdikov VS, Basharin AY, Levashov PR. Two-phase simulation of the crystalline silicon melting line at pressures from –1 to 3 GPa. J Chem Phys 2012; 137:054502. [PMID: 22894359 DOI: 10.1063/1.4739085] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- V S Dozhdikov
- Joint Institute for High Temperatures RAS, Izhorskaya 13 bldg. 2, Moscow 125412, Russia
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20
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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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21
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Wang LG, van de Walle A. Ab initio calculations of the melting temperatures of refractory bcc metals. Phys Chem Chem Phys 2012; 14:1529-34. [DOI: 10.1039/c1cp23036k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Ismer L, Ireta J, Neugebauer J. A density functional theory based estimation of the anharmonic contributions to the free energy of a polypeptide helix. J Chem Phys 2011; 135:084122. [DOI: 10.1063/1.3629451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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Pozzo M, Alfè D, Lacovig P, Hofmann P, Lizzit S, Baraldi A. Thermal expansion of supported and freestanding graphene: lattice constant versus interatomic distance. PHYSICAL REVIEW LETTERS 2011; 106:135501. [PMID: 21517393 DOI: 10.1103/physrevlett.106.135501] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Indexed: 05/30/2023]
Abstract
By using ab initio molecular dynamics calculations, we show that even where the graphene lattice constant contracts, as previously reported for freestanding graphene below room temperature, the average carbon-carbon distance increases with temperature, in both free and supported graphene. This results in a larger corrugation at higher temperature, which can affect the interaction between graphene and the supporting substrate. For a weakly interacting system as graphene/Ir(111), we confirm the results using an experimental approach which gives direct access to interatomic distances.
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Affiliation(s)
- Monica Pozzo
- Department of Earth Sciences, TYC@UCL, University College London, Gower Street, London WC1E 6BT, United Kingdom
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