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de Villa K, González-Cataldo F, Militzer B. Double superionicity in icy compounds at planetary interior conditions. Nat Commun 2023; 14:7580. [PMID: 37990010 PMCID: PMC10663582 DOI: 10.1038/s41467-023-42958-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 10/27/2023] [Indexed: 11/23/2023] Open
Abstract
The elements hydrogen, carbon, nitrogen and oxygen are assumed to comprise the bulk of the interiors of the ice giant planets Uranus, Neptune, and sub-Neptune exoplanets. The details of their interior structures have remained largely unknown because it is not understood how the compounds H2O, NH3 and CH4 behave and react once they have been accreted and exposed to high pressures and temperatures. Here we study thirteen H-C-N-O compounds with ab initio computer simulations and demonstrate that they assume a superionic state at elevated temperatures, in which the hydrogen ions diffuse through a stable sublattice that is provided by the larger nuclei. At yet higher temperatures, four of the thirteen compounds undergo a second transition to a novel doubly superionic state, in which the smallest of the heavy nuclei diffuse simultaneously with hydrogen ions through the remaining sublattice. Since this transition and the melting transition at yet higher temperatures are both of first order, this may introduce additional layers in the mantle of ice giant planets and alter their convective patterns.
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Affiliation(s)
- Kyla de Villa
- Department of Earth and Planetary Science, University of California, Berkeley, CA, 94720, USA.
| | - Felipe González-Cataldo
- Department of Earth and Planetary Science, University of California, Berkeley, CA, 94720, USA
| | - Burkhard Militzer
- Department of Earth and Planetary Science, University of California, Berkeley, CA, 94720, USA
- Department of Astronomy, University of California, Berkeley, CA, 94720, USA
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2
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Ding C, Yuan J, Han Y, Zhang Z, Jia Q, Wang J, Sun J. Purely single-bonded spiral nitrogen chains stabilized by trivalent lanthanum ions. J Chem Phys 2023; 159:184703. [PMID: 37942868 DOI: 10.1063/5.0176226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 10/13/2023] [Indexed: 11/10/2023] Open
Abstract
Inspired by the single-bonded nitrogen chains stabilized by tetravalent cerium, pentavalent tantalum, and hexavalent tungsten atoms, we explored the possibility of single-bonded nitrogen polymorphs stabilized by trivalent lanthanum ions. To achieve this, we utilized the crystal structure search method on the phase diagram of binary La-N compounds. We identified three novel thermodynamically stable phases, the C2/c LaN3, P-1 LaN4, and P-1 LaN8. Among them, the C2/c phase with infinite helical poly-N6 chains becomes thermodynamically stable above 50 GPa. Each nitrogen atom in the poly-N6 chain acquires one extra electron, and the spiral chain is purely single-bonded. The C2/c phase has an indirect band gap of ∼1.6 eV at 60 GPa. Notably, the band gap exhibits non-monotonic behavior, decreases first and then increases with increasing pressure. This abnormal behavior is attributed to the significant bonding of two La-N bonds at around 35 GPa. Phonon spectrum calculations and AIMD simulations have confirmed that the C2/c phase can be quenched to ambient conditions with slight distortion, and it exhibits excellent detonation properties. Additionally, we also discovered armchair-like nitrogen chains in LaN4 and the armchair and zigzag-like mixed nitrogen chains in LaN8. These results provide valuable insights into the electronic and bonding properties of nitrides under high pressure and may have important implications for the design and development of novel functional materials.
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Affiliation(s)
- Chi Ding
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jianan Yuan
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- School of Physics and Electronic Information, Yantai University, Yantai 264005, China
| | - Yu Han
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Zhongwei Zhang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Qiuhan Jia
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Junjie Wang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jian Sun
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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3
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Sharma V, Collins LA, White AJ. Stochastic and mixed density functional theory within the projector augmented wave formalism for simulation of warm dense matter. Phys Rev E 2023; 108:L023201. [PMID: 37723794 DOI: 10.1103/physreve.108.l023201] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 05/08/2023] [Indexed: 09/20/2023]
Abstract
Stochastic density functional theory (DFT) and mixed stochastic-deterministic DFT are burgeoning approaches for the calculation of the equation of state and transport properties in materials under extreme conditions. In the intermediate warm dense matter regime, a state between correlated condensed matter and kinetic plasma, electrons can range from being highly localized around nuclei to delocalized over the whole simulation cell. The plane-wave basis pseudopotential approach is thus the typical tool of choice for modeling such systems at the DFT level. Unfortunately, stochastic DFT methods scale as the square of the maximum plane-wave energy in this basis. To reduce the effect of this scaling and improve the overall description of the electrons within the pseudopotential approximation, we present stochastic and mixed DFT approaches developed and implemented within the projector augmented wave formalism. We compare results between the different DFT approaches for both single-point and molecular dynamics trajectories and present calculations of self-diffusion coefficients of solid density carbon from 1 to 50 eV.
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Affiliation(s)
- Vidushi Sharma
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
- Center for Nonlinear Studies, 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
| | - Alexander J White
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Wang J, Gao H, Han Y, Ding C, Pan S, Wang Y, Jia Q, Wang HT, Xing D, Sun J. MAGUS: machine learning and graph theory assisted universal structure searcher. Natl Sci Rev 2023; 10:nwad128. [PMID: 37332628 PMCID: PMC10275355 DOI: 10.1093/nsr/nwad128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 03/30/2023] [Accepted: 04/28/2023] [Indexed: 06/20/2023] Open
Abstract
Crystal structure predictions based on first-principles calculations have gained great success in materials science and solid state physics. However, the remaining challenges still limit their applications in systems with a large number of atoms, especially the complexity of conformational space and the cost of local optimizations for big systems. Here, we introduce a crystal structure prediction method, MAGUS, based on the evolutionary algorithm, which addresses the above challenges with machine learning and graph theory. Techniques used in the program are summarized in detail and benchmark tests are provided. With intensive tests, we demonstrate that on-the-fly machine-learning potentials can be used to significantly reduce the number of expensive first-principles calculations, and the crystal decomposition based on graph theory can efficiently decrease the required configurations in order to find the target structures. We also summarized the representative applications of this method on several research topics, including unexpected compounds in the interior of planets and their exotic states at high pressure and high temperature (superionic, plastic, partially diffusive state, etc.); new functional materials (superhard, high-energy-density, superconducting, photoelectric materials), etc. These successful applications demonstrated that MAGUS code can help to accelerate the discovery of interesting materials and phenomena, as well as the significant value of crystal structure predictions in general.
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Affiliation(s)
| | | | | | - Chi Ding
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Shuning Pan
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yong Wang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Qiuhan Jia
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Hui-Tian Wang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Dingyu Xing
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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Pan S, Huang T, Vazan A, Liang Z, Liu C, Wang J, Pickard CJ, Wang HT, Xing D, Sun J. Magnesium oxide-water compounds at megabar pressure and implications on planetary interiors. Nat Commun 2023; 14:1165. [PMID: 36859401 PMCID: PMC9977943 DOI: 10.1038/s41467-023-36802-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 02/15/2023] [Indexed: 03/03/2023] Open
Abstract
Magnesium Oxide (MgO) and water (H2O) are abundant in the interior of planets. Their properties, and in particular their interaction, significantly affect the planet interior structure and thermal evolution. Here, using crystal structure predictions and ab initio molecular dynamics simulations, we find that MgO and H2O can react again at ultrahigh pressure, although Mg(OH)2 decomposes at low pressure. The reemergent MgO-H2O compounds are: Mg2O3H2 above 400 GPa, MgO3H4 above 600 GPa, and MgO4H6 in the pressure range of 270-600 GPa. Importantly, MgO4H6 contains 57.3 wt % of water, which is a much higher water content than any reported hydrous mineral. Our results suggest that a substantial amount of water can be stored in MgO rock in the deep interiors of Earth to Neptune mass planets. Based on molecular dynamics simulations we show that these three compounds exhibit superionic behavior at the pressure-temperature conditions as in the interiors of Uranus and Neptune. Moreover, the water-rich compound MgO4H6 could be stable inside the early Earth and therefore may serve as a possible early Earth water reservoir. Our findings, in the poorly explored megabar pressure regime, provide constraints for interior and evolution models of wet planets in our solar system and beyond.
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Affiliation(s)
- Shuning Pan
- grid.41156.370000 0001 2314 964XNational Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093 Nanjing, China
| | - Tianheng Huang
- grid.41156.370000 0001 2314 964XNational Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093 Nanjing, China
| | - Allona Vazan
- grid.412512.10000 0004 0604 7424Astrophysics Research Center of the Open University (ARCO), The Open University of Israel, 4353701 Raanana, Israel
| | - Zhixin Liang
- grid.41156.370000 0001 2314 964XNational Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093 Nanjing, China
| | - Cong Liu
- grid.41156.370000 0001 2314 964XNational Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093 Nanjing, China
| | - Junjie Wang
- grid.41156.370000 0001 2314 964XNational Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093 Nanjing, China
| | - Chris J. Pickard
- grid.5335.00000000121885934Theory of Condensed Matter Group, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge, CB3 0HE UK ,grid.69566.3a0000 0001 2248 6943Advanced Institute for Materials Research, Tohoku University 2-1-1 Katahira, Aoba, Sendai, 980-8577 Japan
| | - Hui-Tian Wang
- grid.41156.370000 0001 2314 964XNational Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093 Nanjing, China
| | - Dingyu Xing
- grid.41156.370000 0001 2314 964XNational Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093 Nanjing, China
| | - Jian Sun
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093, Nanjing, China.
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Kovačević T, González-Cataldo F, Stewart ST, Militzer B. Miscibility of rock and ice in the interiors of water worlds. Sci Rep 2022; 12:13055. [PMID: 35906271 PMCID: PMC9338078 DOI: 10.1038/s41598-022-16816-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 07/15/2022] [Indexed: 11/17/2022] Open
Abstract
Super-Earths and sub-Neptunes are the most common planet types in our galaxy. A subset of these planets is predicted to be water worlds, bodies that are rich in water and poor in hydrogen gas. The interior structures of water worlds have been assumed to consist of water surrounding a rocky mantle and iron core. In small planets, water and rock form distinct layers with limited incorporation of water into silicate phases, but these materials may interact differently during the growth and evolution of water worlds due to greater interior pressures and temperatures. Here, we use density functional molecular dynamics (DFT-MD) simulations to study the miscibility and interactions of enstatite (MgSiO3), a major end-member silicate phase, and water (H2O) at extreme conditions in water world interiors. We explore pressures ranging from 30 to 120 GPa and temperatures from 500 to 8000 K. Our results demonstrate that enstatite and water are miscible in all proportions if the temperature exceeds the melting point of MgSiO3. Furthermore, we performed smoothed particle hydrodynamics simulations to demonstrate that the conditions necessary for rock-water miscibility are reached during giant impacts between water-rich bodies of 0.7–4.7 Earth masses. Our simulations lead to water worlds that include a mixed layer of rock and water.
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Affiliation(s)
- Tanja Kovačević
- Department of Earth and Planetary Science, University of California, Berkeley, CA, 94720, USA.
| | - Felipe González-Cataldo
- Department of Earth and Planetary Science, University of California, Berkeley, CA, 94720, USA
| | - Sarah T Stewart
- Department of Earth and Planetary Sciences, University of California, Davis, CA, 95616, USA
| | - Burkhard Militzer
- Department of Earth and Planetary Science, University of California, Berkeley, CA, 94720, USA.,Department of Astronomy, University of California, Berkeley, CA, 94720, USA
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Li HF, Oganov AR, Cui H, Zhou XF, Dong X, Wang HT. Ultrahigh-Pressure Magnesium Hydrosilicates as Reservoirs of Water in Early Earth. PHYSICAL REVIEW LETTERS 2022; 128:035703. [PMID: 35119889 DOI: 10.1103/physrevlett.128.035703] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 12/03/2021] [Accepted: 12/23/2021] [Indexed: 06/14/2023]
Abstract
The origin of water on the Earth is a long-standing mystery, requiring a comprehensive search for hydrous compounds, stable at conditions of the deep Earth and made of Earth-abundant elements. Previous studies usually focused on the current range of pressure-temperature conditions in the Earth's mantle and ignored a possible difference in the past, such as the stage of the core-mantle separation. Here, using ab initio evolutionary structure prediction, we find that only two magnesium hydrosilicate phases are stable at megabar pressures, α-Mg_{2}SiO_{5}H_{2} and β-Mg_{2}SiO_{5}H_{2}, stable at 262-338 GPa and >338 GPa, respectively (all these pressures now lie within the Earth's iron core). Both are superionic conductors with quasi-one-dimensional proton diffusion at relevant conditions. In the first 30 million years of Earth's history, before the Earth's core was formed, these must have existed in the Earth, hosting much of Earth's water. As dense iron alloys segregated to form the Earth's core, Mg_{2}SiO_{5}H_{2} phases decomposed and released water. Thus, now-extinct Mg_{2}SiO_{5}H_{2} phases have likely contributed in a major way to the evolution of our planet.
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Affiliation(s)
- Han-Fei Li
- Key Laboratory of Weak-Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China
| | - Artem R Oganov
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, Bolshoy Boulevard 30, Building 1, Moscow 121205, Russia
| | - Haixu Cui
- College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, China
| | - Xiang-Feng Zhou
- Center for High Pressure Science, State Key Laboratory of Metastable Materials Science and Technology, School of Science, Yanshan University, Qinhuangdao 066004, China
| | - Xiao Dong
- Key Laboratory of Weak-Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China
| | - Hui-Tian Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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Schirber M. Mineral Candidates for Planet Interiors. PHYSICS 2022. [DOI: 10.1103/physics.15.9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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