Article
Chemistry, Multidisciplinary
Piotr A. Gunka, Michael Hanfland, Yu-Sheng Chen, Janusz Zachara
Summary: High-pressure structural studies of arsenic(III) oxide polymorphs reveal that claudetite I is the densest and least compressible ambient-pressure As2O3 polymorph, with no phase transitions under high pressure or low temperature. The coordination sphere of arsenic atoms is thoroughly characterized, showing that claudetite I does not exhibit the highest coordination numbers despite being the densest polymorph. The pressure dependence of As-O bond lengths and stereoactivity of arsenic lone electron pairs are also investigated, demonstrating consistent behaviors across different As2O3 polymorphs.
Article
Physics, Multidisciplinary
Wei Liu, Boqiang Wu, Ze'an Tian, Yunfei Mo, Tingfei Xi, Zhiyi Wan, Rangsu Liu, Hairong Liu
Summary: The study using molecular dynamics simulations revealed that pressure has a significant influence on the structural properties and dynamics of magnesium during rapid solidification, resulting in denser structures and structural transformations. Additionally, investigation of the phonon dispersion of magnesium under different pressures provided insights into polymorphic transitions and guidance for selecting magnesium polymorphs for practical applications.
Article
Materials Science, Multidisciplinary
Emilie Dufault, Faranak Bahrami, Alenna Streeter, Xiaohan Yao, Enrique Gonzalez, Qiang Zhang, Fazel Tafti
Summary: Recent theoretical studies have revealed that anisotropic Kitaev interactions could dominate the low-energy Hamiltonian of honeycomb cobaltate systems. In this study, a honeycomb layered material Na2Co2TeO6 with a hexagonal unit cell was investigated, exhibiting antiferromagnetic (AFM) ordering at 27 K with spin reorientation transitions at 15 and 5 K. A monoclinic polymorph of Na2Co2TeO6, also with a honeycomb layered structure, was discovered to have a single AFM transition at 9.6 K without spin reorientation at lower temperatures. Neutron diffraction revealed an in-plane zigzag AFM order in the ground state, with spins canted out of the honeycomb planes and ferromagnetically coupled between them. The zigzag order is suppressed by a 6 T magnetic field. The lower critical temperature and field, positive Curie-Weiss temperature, and out-of-plane canting of spins in monoclinic Na2Co2TeO6 suggest enhanced frustration compared to the hexagonal polymorph.
Article
Chemistry, Physical
Siree Burapornpong, Shota Tsuchiya, Toru Kimura, Atsunori Kamegawa
Summary: In this study, a novel compound in the Mg-Y system was investigated using high-pressure synthesis technique, where crystal structure, thermal stability, and hydrogenation properties of the compound were evaluated. The research found that Mg3Y can decompose into Mg24Y5 and Mg2Y phases under specific conditions, and hydrogenation of Mg3Y resulted in the formation of MgH2 and YH3 phases. Additionally, comparison experiments were conducted between Mg3Y and Mg3La, showing that the latter can form a hydride at higher pressures.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Haiyan Yan, Lei Chen, Jiahui Peng, Xin Chang, Peifang Li, Meiguang Zhang, Qun Wei
Summary: The pressure-induced phase transitions of MoAlB have revealed a novel high-pressure monoclinic structure, characterized by slip in metallic Al-Al layers and fracture of linear zigzag B-B chains under compression. The study also demonstrates a first-order structure transition from the ambient-pressure orthorhombic phase to this high-pressure monoclinic phase, supported by softening of elastic constant. Phonon curves calculations indicate that the high-pressure phase can be quenchable to ambient pressure, and the electronic and mechanical properties of this new phase have been systematically investigated.
RESULTS IN PHYSICS
(2021)
Article
Physics, Multidisciplinary
Qing-Yang Fan, Chen-Si Li, Ying-Bo Zhao, Yan-Xing Song, Si-Ning Yun
Summary: In this study, a new superhard material, Pm BN, is proposed and its structural properties, stability, mechanical properties, mechanical anisotropy properties, and electronic properties are investigated. The results show that Pm BN is stable and mechanically superior to other boron nitride materials, with significant mechanical anisotropy.
COMMUNICATIONS IN THEORETICAL PHYSICS
(2022)
Article
Physics, Condensed Matter
A. B. Garg, D. Errandonea, P. Rodriguez-Hernandez, A. Munoz
Summary: This study investigates the high-pressure behavior of fergusonite-type HoNbO4, revealing a reversible phase transition and differences in structural behavior compared to related niobates. The transition involves a change in Nb coordination number and is driven by mechanical instabilities. The study also includes pressure-dependent measurements, as well as identification of active modes and elastic constants through simulations.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Chemistry, Physical
Kelly M. Powderly, Shu Guo, Hillary E. Mitchell Warden, Loi T. Nguyen, R. J. Cava
Summary: Metastable phase beta-NdCo2B2 with a new triclinic structure type was synthesized and characterized, displaying metallic conductivity and complex magnetic properties. Density functional theory calculations were used to explore the stability, magnetism, and electronic structure of beta-NdCo2B2.
CHEMISTRY OF MATERIALS
(2021)
Article
Chemistry, Inorganic & Nuclear
Fabian Zimmerhofer, Hubert Huppertz
Summary: This paper presents a new high-pressure polymorph of oxyfluoride K2MoO2F4, with its crystal structure determined using single-crystal X-ray diffractometry. The features of the crystal structure are described in detail, and calculations are conducted to support the assignment of oxygen and fluorine positions. Infrared spectroscopy provides additional information on the structure and water content of the inseparable side phase.
DALTON TRANSACTIONS
(2023)
Article
Nanoscience & Nanotechnology
Daniel L. Bodine, Angus P. Wilkinson
Summary: A new tetragonal polymorph of CaZrF6 is synthesized by high energy ball milling of a CaF2/ZrF4 mixture, followed by heat treatment. This polymorph is thermodynamically stable at low temperatures but transforms to the cubic form when heated above 400 degrees C. Unlike the well-known cubic form, the tetragonal form exhibits positive thermal expansion in all directions.
Article
Physics, Condensed Matter
Xin Bao, Hongyun Lang, Xinjun Ma, Tianji Ou, Meiguang Zhang, Xinxin Zhang, Peifang Li
Summary: In this study, the high-pressure phase transitions of Sn were investigated using the CALYPSO structure prediction method and first-principles calculations. Experimental structures were successfully reproduced, and a novel high-pressure structure was discovered. The results of elastic constants and phonon dispersion curves indicated the stability of the new structure. This research enriches the understanding of high-pressure phases of Sn and lays the groundwork for future theoretical and experimental studies.
SOLID STATE COMMUNICATIONS
(2022)
Article
Chemistry, Inorganic & Nuclear
Danrui Ni, Haozhe Wang, Xianghan Xu, Weiwei Xie, Robert J. Cava
Summary: A layered rhombohedral polymorph of indium(iii) triiodide is synthesized at high pressure and temperature. It has an orange color, which is different from ambient pressure InI3, which has a monoclinic molecular structure and a light-yellow color.
DALTON TRANSACTIONS
(2024)
Article
Multidisciplinary Sciences
I. B. Rietveld, M. Barrio, R. Ceolin, J. Ll. Tamarit
Summary: For a long time, it was believed that the crystalline polymorph II of benzophenone does not have a stable domain in the pressure-temperature phase diagram. However, through a combination of new experimental results and literature data, it has been shown that form II does have a stable domain at high pressure and high temperature. This discovery emphasizes the importance of considering both heat exchange and work when understanding the phase behavior of chemical substances.
SCIENTIFIC REPORTS
(2023)
Article
Physics, Multidisciplinary
Maxim Bykov, Timofey Fedotenko, Stella Chariton, Dominique Laniel, Konstantin Glazyrin, Michael Hanfland, Jesse S. Smith, Vitali B. Prakapenka, Mohammad F. Mahmood, Alexander F. Goncharov, Alena Ponomareva, Ferenc Tasnadi, Alexei Abrikosov, Talha Bin Masood, Ingrid Hotz, Alexander N. Rudenko, Mikhail Katsnelson, Natalia Dubrovinskaia, Leonid Dubrovinsky, Igor A. Abrikosov
Summary: High-pressure chemistry has led to the synthesis of a new class of 2D material, BeN4, consisting of polyacetylene-like nitrogen chains and Be atoms in square-planar coordination. The BeN4 layer represents a qualitatively new class of materials that can host anisotropic Dirac fermions.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Inorganic & Nuclear
Michael O. Ogunbunmi, Sviatoslav Baranets, Svilen Bobev
Summary: The Zintl phase Ca2CdSb2 was found to be dimorphic, with its monoclinic form, Ca2CdSb2 (-m), exhibiting complex structural characteristics and potential thermoelectric properties. Doping with Lu resulted in a transition from a semiconductor to a degenerate p-type semiconductor, and both phases showed low thermal conductivity, indicating their potential as moderate temperature thermoelectric materials.
INORGANIC CHEMISTRY
(2022)
Article
Computer Science, Interdisciplinary Applications
Michele Galasso, Artem R. Oganov
Summary: We developed a Python package for finding the lowest-energy magnetic state and estimating the critical temperature of a given structure. The code was tested on known materials and successfully predicted the magnetic ground state and Neel temperature for some of them. However, it failed to reproduce the experimental results for a specific material.
COMPUTER PHYSICS COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Dmitry V. Rybkovskiy, Sergey V. Lepeshkin, Vladimir S. Baturin, Anastasiia A. Mikhailova, Artem R. Oganov
Summary: Through analyzing stable phosphorus clusters, we find that elemental phosphorus has various allotropes. The ground-state structures of P-n clusters in a wide range of compositions are determined using density functional calculations and global optimization techniques. We explain the reason why high-energy white phosphorus is easily formed compared to more stable allotropes. Investigation of relative stability reveals even-odd alternations and structural magic numbers.
Article
Physics, Multidisciplinary
V. I. Anisimov, A. R. Oganov, M. A. Mazannikova, D. Y. Novoselov, Dm. M. Korotin
Summary: KMnO4 has an unusual formal manganese valence state of Mn+7, which is puzzling due to the high energy required to create this ion compared to the energy of chemical bonds. A study using the Wannier functions formalism reveals that, although the formal configuration of the manganese ion in this compound is d0, only about half of the hole density described by these functions belongs to d-electrons, while the other half is distributed among the surrounding oxygen atoms. This suggests a closer resemblance to Mn(+2) rather than Mn+7, as the calculated total number of d-electrons is 5.25. Additionally, the analysis demonstrates a nearly perfect covalent type of chemical bond, with a minor contribution from ionic bonding.
Article
Chemistry, Physical
Bo Gyu Jang, Yu He, Ji Hoon Shim, Ho-kwang Mao, Duck Young Kim
Summary: The Earth's inner core is composed primarily of iron and some light elements, but studying its structure and properties has been challenging due to the extreme pressure and temperature conditions required. In this study, it was found that the presence of oxygen enhances the electron correlation effect and affects important features, such as the stability of iron oxides. Oxygen stabilizes hexagonal-structured iron and induces elastic anisotropy under inner core conditions. The electrical resistivity is significantly increased due to the enhanced electron correlation effect, supporting the conventional thermal convection model. Additionally, the calculated seismic velocity matches well with geologically observed data, suggesting that oxygen is a crucial light element for understanding and modeling Earth's inner core.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Hong-Mei Huang, Qiang Zhu, Vladislav A. Blatov, Artem R. Oganov, Xiaoting Wei, Peng Jiang, Yan-Ling Li
Summary: In this study, we used an evolutionary crystal structure prediction algorithm and first-principles calculations to determine the phase diagram and electronic properties of the Li-Cs system. We found that Li-rich compounds are easily formed in a wide pressure range, while LiCs3 is the only Cs-rich compound that is thermodynamically stable at pressures above 359 GPa. Furthermore, our analysis of crystal structures revealed unique topologies in Li6Cs and Li14Cs, which have not been reported in existing intermetallics. Additionally, we discovered four Li-rich compounds (Li14Cs, Li8Cs, Li7Cs, and Li6Cs) that exhibit superconductivity with a high critical temperature, attributed to their distinctive structural topologies and charge transfer between Li and Cs atoms. This research enhances our understanding of the high-pressure behavior of intermetallic compounds and offers a new approach for designing new superconductors.
Article
Biochemistry & Molecular Biology
Pavel Rachitskii, Ivan Kruglov, Alexei V. Finkelstein, Artem R. Oganov
Summary: Protein structure prediction is a major problem in modern biophysics. Current methods that use big data and machine learning have achieved success in recognizing tertiary protein structure from amino acid sequences. In this study, we extended the evolutionary algorithm USPEX to predict protein structure based on global optimization. Our algorithm achieved high accuracy in predicting the tertiary structures of proteins.
PROTEINS-STRUCTURE FUNCTION AND BIOINFORMATICS
(2023)
Article
Multidisciplinary Sciences
Shichuan Sun, Yu He, Junyi Yang, Yufeng Lin, Jinfeng Li, Duck Young Kim, Heping Li, Ho-kwang Mao
Summary: Seismological observations suggest that Earth's inner core is heterogeneous and anisotropic. A new study based on computational simulation reveals the presence of ionic hydrogen flux in iron crystals, driven by the dipole geomagnetic field, which promotes the formation of observed inner core structure.
NATURE COMMUNICATIONS
(2023)
Article
Crystallography
Alexey P. Maltsev, Ilya V. Chepkasov, Alexander G. Kvashnin, Artem R. Oganov
Summary: We comprehensively study the ionic conductivity in lithium phosphides using first-principles computations and machine learning interatomic potentials. The temperature-composition phase diagram was obtained and the ionic conductivity of different compounds was studied. Some compounds exhibit high ionic conductivity at room temperatures. This study provides insights for the development of Li-P materials in battery applications.
Article
Nanoscience & Nanotechnology
Alexey P. Maltsev, Ilya V. Chepkasov, Artem R. Oganov
Summary: In this study, temperature-induced phase transitions and ionic conductivities of Li2B12H12 and LiCB11H12 were simulated using machine learning interatomic potentials. The results are in good agreement with experimental data, and the importance of reorientational motion in the phase transition was uncovered.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Physical
Elizaveta E. Vaneeva, Sergey V. Lepeshkin, Artem R. Oganov
Summary: This study investigates the chemical diversity of CmNnHk molecules using molecular magicity criteria, evolutionary structure prediction, and quantum-chemical calculations. The predicted magic molecules are in agreement with compounds found in various environments, demonstrating the predictive power of the approach.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Ivan A. Kruglov, Alexey V. Yanilkin, Yana Propad, Arslan B. Mazitov, Pavel Rachitskii, Artem R. Oganov
Summary: Crystal structure prediction, a long-standing problem in crystallography and materials science, has been largely solved with methods such as energy landscape exploration and global optimization. However, existing methods neglect temperature and may miss high-temperature phases. In this study, a new and cost-effective solution is developed to predict crystal structures at finite temperatures, taking into account thermal effects and providing accurate results.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Anastasiia A. A. Mikhailova, Sergey V. V. Lepeshkin, Vladimir S. S. Baturin, Alexey P. P. Maltsev, Yurii A. A. Uspenskii, Artem R. R. Oganov
Summary: Systematic structure prediction of CunAum nanoclusters for CO oxidation catalysis was performed using USPEX algorithm and DFT calculations. The selected clusters were further investigated for their catalytic properties including adsorption energies, reaction paths, and activation energies. The Cu7Au6 cluster exhibited extremely low activation energies for all transition states, indicating the high catalytic activity due to the flexibility of binary nanoclusters. Therefore, Cu-Au nanoparticles are promising catalysts considering the lower cost of copper.
Article
Materials Science, Multidisciplinary
Sergey Pozdnyakov, Artem R. Oganov, Efim Mazhnik, Arslan Mazitov, Ivan Kruglov
Summary: We introduce a new class of machine learning interatomic potentials called fast general two-and three-body potential (GTTP), which is as fast as conventional empirical potentials and has a constant computational time. GTTP can accurately model two-and three-body interactions using thousands of parameters. The potential is obtained through simple linear regression on ab initio calculated energies and forces, resulting in accurate reproduction of quantum many-body interactions. Our potential outperforms common empirical potentials on the study of large systems, such as grain boundaries in polycrystalline materials, when trained on randomly generated structures with just eight atoms in the unit cell.
Article
Chemistry, Physical
Maria Fedyaeva, Sergey Lepeshkin, Artem R. Oganov
Summary: With the use of ab initio evolutionary algorithm USPEX, we were able to predict the structures of sulfur molecules S-n (n = 2 - 21). Our findings show that sulfur molecules with n >= 5 have stable closed helical ring structures, which aligns with experimental data and previous calculations. By examining second-order energy difference (Delta E-2), fragmentation energy (E-frag), and HOMO-LUMO gaps, we evaluated the stability of these molecules. The S-8 molecule exhibited the highest Delta E-2 value and forms the most commonly found allotropic form of sulfur, while S-12 and S-6 also showed strong positive Delta E-2 values.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Dmitry Y. Novoselov, Mary A. Mazannikova, Dmitry M. Korotin, Alexey O. Shorikov, Vladimir I. Anisimov, Artem R. Oganov
Summary: This study investigates the role of interstitial electronic states in the metal-to-semiconductor transition in Ca2N and the origin of the volume collapse during pressure-induced phase transitions. It emphasizes the importance of correlation effects in the electride subsystem in the complex phase transformation mechanism. By using a simplified model and solving it with Dynamical Mean Field Theory, the evolution between the metallic and semiconducting phases and the significant volume collapse were successfully reproduced.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
