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AffiliationAutonomous Non-Profit Organization for Higher Education "Skolkovo Institute of Science and Technology",

Research area 02 - PHYSICS AND SPACE SCIENCES, 02-201 - Theory of condensed matter

Keywordscomputational materials design, evolutionary algorithms, crystal structure prediction, strongly correlated systems

Annotation
This project aims to develop new computational techniques and methods that will y significantly increase the scope of computational materials discovery, allowing much more complex materials to be predicted, new classes of materials to become amenable to structure prediction, to include the “difficult” effects of temperature and electron correlations. Two flagship Russian codes in this field, USPEX and Amulet, will be interfaced, and their complementary capabilities exploited to the maximum in a tandem. Therefore, this project will benefit the entire international scientific community by giving it improved versions of these powerful flagship codes. The new methods will be used for solving a number of major fundamental and especially applied problems related to the discovery of: -novel superhard materials, with prospects also use in drilling technologies, ballistic vests, machining tools, surgical equipment, bullet and projectile heads, etc. -novel permanent magnets, to lift the dependency on the rare earth supply. Such materials are used throughout modern world, for example, in superfact Maglev trains. -novel thermoelectric materials, with the aim of increasing the efficiency of some electric devices by a factor of 2-3. Thermoelectric power conversion is perhaps the only way to generate electricity in remote areas, or in outer space. This effect can also be used for increasing efficiency of power plant, car engines etc. -electrides, a unique class of materials with strongly localized the electrons (localized in cavities of the structure) and which can be used as catalysts and as electron emitters. -nanoparticles with catalytic activity or promising electronic properties. Catalysis is the basis of chemical industry, it’s a hugely important theme. Plasmonic nanoparticles are a very hot topic, and we would like to explore it.

Expected results
Our project is intrinsically pragmatic, oriented towards applications. Each successfully found material gives a huge economic and technological effect.

Annotation of the results obtained in 2022
Our project is focused on the development and application of computer prediction methods for new materials. In 2022, significant results were achieved that have both fundamental and applied value. In the methodological part, this includes the development of a method for predicting crystal structures at finite temperatures (previously, the prediction of crystal structures was done only at zero Kelvin), the prediction of stable molecules and clusters, the prediction of new magnetic materials, and the prediction of molecular crystal structures. The problem of predicting crystal structures at finite temperatures was solved using machine-learned interatomic potentials, which can be used for quick estimation of the free energy, and the residual error of the interatomic potential is extinguished using thermodynamic perturbation theory. To predict new magnetic materials, the USPEX method was extended to include new variational operators and new fitness functions. The new method obtained in this way makes it possible to simultaneously optimize the crystal structure, chemical composition and magnetic structure of a substance. Another direction of the research is the prediction of stable molecules, which requires new methodological techniques and has been applied by us to a number of important systems (B, S, and also hydrocarbons). Our results helped to understand the diversity of sulfur modifications (the preference for the formation of cyclic molecules S8, as well as S12 and S6) and the nature of the chemical diversity of hydrocarbons. It turned out that a huge amount of chemical information about hydrocarbons can be systematized using the stability map of hydrocarbon molecules that we obtained. With the help of the methods we developed, we focused on several interesting classes of materials. For example, for polyhydrides with high-temperature superconductivity, we discovered a new physical effect: a linear dependence of the critical magnetic field on temperature. A unique substance SrH22 was discovered with a record hydrogen content of all known metal hydrides. The La-Ce-H ternary hydride has also been found to be stable at lower pressures than other high temperature superconducting hydrides. On the basis of electronic and structural analogy, a hypothesis was put forward that copper fluorides can be high-temperature superconductors similar to cuprates. A number of interesting results were obtained in high-pressure chemistry and physics, in particular, a huge variety of silver fluorides was predicted both under normal conditions and at high pressures. Unusual physical phenomena in new exotic iron oxides were studied using advanced methods for studying highly correlated systems, such as DFT + DMFT. At high pressures, a new high-energy modification of potassium azide K2N6 with six-membered hexine rings N6 was obtained. A new substance, stable at high pressures, Mg2SiO5H2, was predicted; in the modern Earth, this substance cannot exist, but at the beginning of the Earth's history it could store water on our planet. The most important achievement in the field of high pressure chemistry was the creation of electronegativity and chemical hardness scales for all elements up to pressures of 500 GPa. These scales have made it possible to explain most of the known anomalies in high-pressure chemistry. Another interesting class of substances on which we focused in detail were electrides - substances in the structural voids of which valence electrons are localized. The most well-known electride, the complex calcium aluminate mayenite, has long been controversial, since theoretical studies based on density functional theory did not show electron localization. We have been able to show that localization arises as a result of electron correlation effects. Thus, taking into account electron correlations it turns out to be important in the study of electrides that do not even contain d- or f-electrons.

Publications

1. Fedyaeva M., Lepeshkin S., Oganov A.R. Stability of sulfur molecules and insights into sulfur allotropy Physical Chemistry Chemical Physics, Vol. 25, Issue 13, P. 9294-9299 (year - 2023) https://doi.org/10.1039/D2CP05498A

2. Pozdnyakov S., Oganov A.R., Mazhnik E., Mazitov A., Kruglov I. Fast general two- and three-body interatomic potential Physical Review B, Vol. 107, Issue 12, P. 125160 (year - 2023) https://doi.org/10.1103/PhysRevB.107.125160

3. Rachitskii P., Kruglov I.A., Finkelstein A.V., Oganov A.R. Protein structure prediction using the evolutionary algorithm USPEX Proteins: Structure, Function, and Bioinformatics, Vol. 91, Issue 7, P. 933-943 (year - 2023) https://doi.org/10.1002/prot.26478

4. Zhou D., Semenok D.V., Volkov M.A., Troyan I.A., Seregin A.Yu., Chepkasov I.V., Sannikov D.A., Lagoudakis P.G., Oganov A.R., German K.E. Synthesis of technetium hydride TcH1.3 at 27 GPa Physical Review B, Vol. 107, Issue 6, p.064102 (year - 2023) https://doi.org/10.1103/PhysRevB.107.064102

5. Abardeh Z.M., Salimi A., Oganov A.R. Crystal structure prediction of N-halide phthalimide compounds: halogen bonding synthons as a touchstone CrystEngComm, CrystEngComm, 2022, 24, 6066-6075 (year - 2022) https://doi.org/10.1039/D2CE00476C

6. Belozerov A.S., Katanin A.A., Anisimov V.I. Coulomb correlations and magnetic properties of L10 FeCo: A DFT+DMFT study PHYSICAL REVIEW MATERIALS, Phys. Rev. Materials 6, 055004 (year - 2022) https://doi.org/10.1103/PhysRevMaterials.6.055004

7. Chernov E.D., Dyachenko A.A., Lukoyanov A.V. Effect of Doping on the Electronic Structure of the Earth’s Lower Mantle Compounds: FeXO3 with X = C, Al, Si Materials, Materials 2022, 15(3), 1080; (year - 2022) https://doi.org/10.3390/ma15031080

8. Dmitrii V. Semenok, Wuhao Chen, Xiaoli Huang, Di Zhou, Ivan A. Kruglov, Arslan B. Mazitov, Michele Galasso, Christian Tantardini, Xavier Gonze, Alexander G. Kvashnin, Artem R. Oganov, and Tian Cui Sr-Doped Superionic Hydrogen Glass: Synthesis and Properties of SrH22 Advanced Materials, Advanced Materials. – 2022. – С. 2200924. (year - 2022) https://doi.org/10.1002/adma.202200924

9. Donga X., Oganov A.R., Cuic H., Zhoud X-F., Wang H.T. Electronegativity and chemical hardness of elements under pressure Proceedings of the National Academy of Sciences, PNAS 2022 Vol. 119 No. 10 e2117416119 (year - 2022) https://doi.org/10.1073/pnas.2117416119

10. Dyachenko A.A., Lukoyanov A.V., Anisimov V.I., Oganov A.R. Electride properties of ternary silicide and germanide of La and Ce PHYSICAL REVIEW B, Phys. Rev. B 105, 085146 (year - 2022) https://doi.org/10.1103/PhysRevB.105.085146

11. Koshkaki S.R., Allahyari Z., Oganov A.R., Solozhenko V.L., Polovov I.B., Belozerov A.S., Katanin A.A., Anisimov V.I., Tikhonov E.V., Qian G.R., Maksimtsev K.V., Mukhamadeev A.S., Chukin A.V., Korolev A.V., Mushnikov N.V., Li H. Computational prediction of new magnetic materials The Journal of Chemical Physics, Journal of Chemical Physics, American Institute of Physics, 2022, 157 (12), pp.124704. 10.1063/5.0113745. hal-03791608 (year - 2022) https://doi.org/10.1063/5.0113745

12. Krichevsky D.M., Shi L., Baturin V.S., Rybkovsky D.V., Wu Y., Fedotov P.V., Obraztsova E.D., Kapralov P.O., Shilina P.V., Fung K., Stoppiello C.T., Belotelov V.I., Khlobystov A., Chernov A.I. Magnetic nanoribbons with embedded cobalt grown inside single-walled carbon nanotubes Nanoscale, Nanoscale, 2022, 14, 1978-1989 (year - 2022) https://doi.org/10.1039/D1NR06179H

13. Kvashnin A.G., Nikitin D.S., Shanenkov I.I., Chepkasov I.V., Kvashnina Y.A., Nassyrbayev A., Sivkov A.A., Bolatova Z., Pak A.Ya. Large-Scale Synthesis and Applications of Hafnium– Tantalum Carbides Advanced Functional Materials, Adv. Funct. Mater. 2022, 2206289 (year - 2022) https://doi.org/10.1002/adfm.202206289

14. Layek S., Greenberg E., Chariton S., Bykov M., Bykova E., Trots D.M., Kurnosov A.V., Chuvashova I., Ovsyannikov S.V., Leonov I., Rozenberg G. Kh. Verwey-Type Charge Ordering and Site-Selective Mott Transition in Fe4O5 under Pressure Journal of the American Chemical Society, J. Am. Chem. Soc. 2022, 144, 23, 10259–10269 (year - 2022) https://doi.org/10.1021/jacs.2c00895

15. Lepeshkin S.V., Baturin V.S., Naumova A.S., Oganov A.R. “Magic” Molecules and a New Look at Chemical Diversity of Hydrocarbons The Journal of Physical Chemistry Letters, J. Phys. Chem. Lett. 2022, 13, 32, 7600–7606 (year - 2022) https://doi.org/10.1021/acs.jpclett.2c02098

16. Li H-F., Oganov A.R., Cui H., Zhou X-F., Dong X., Wang H-T. Ultrahigh-Pressure Magnesium Hydrosilicates as Reservoirs of Water in Early Earth PHYSICAL REVIEW LETTERS, Phys. Rev. Lett. 128, 035703 (year - 2022) https://doi.org/10.1103/PhysRevLett.128.035703

17. Marchenko E.I., Oganov A.R., Mazhnik E.A., Eremin N.N. Stable compounds in the CaO‑Al2O3 system at high pressures Physics and Chemistry of Minerals, Phys Chem Minerals 49, 44 (2022) (year - 2022) https://doi.org/10.1007/s00269-022-01221-6

18. Novoselov D.Y., Mazannikova M.A., Korotin D.M, Shorikov A.O., Korotin M.A., Anisimov V.I., Oganov A.R. Localization Mechanism of Interstitial Electronic States in Electride Mayenite The Journal of Physical Chemistry Letters, J. Phys. Chem. Lett. 2022, 13, 31, 7155–7160 (year - 2022) https://doi.org/10.1021/acs.jpclett.2c02002

19. Pak A.Ya., Rybkovskiy D.V., Vassilyeva Y.Z., Kolobova E.N., Filimonenko A.F., Kvashnin A.G. Efficient Synthesis of WB5−x−WB2 Powders with Selectivity for WB5−x Content Inorganic Chemistry, Inorg. Chem. 2022, 61, 18, 6773–6784 (year - 2022) https://doi.org/10.1021/acs.inorgchem.1c03880

20. Rybin N., Chepkasov I., Novoselov D.Y., Anisimov V.I., Oganov A.R. Prediction of Stable Silver Fluorides Journal of Physical Chemistry C, J. Phys. Chem. C 2022, 126, 35, 15057–15063 (year - 2022) https://doi.org/10.1021/acs.jpcc.2c04785

21. Semenok D.V., Troyan I.A., Sadakov A.V., ... , Pudalov V.M., Lyubutin I.S., Oganov A.R. Effect of Magnetic Impurities on Superconductivity in LaH10 Advanced Materials, 34, 42, 2204038 (year - 2022) https://doi.org/10.1002/adma.202204038

22. Shorikov A.O., Streltsov S.V. Importance of the many-body effects on the structural properties of the novel iron oxide Fe2O physical chemistry chemical physics, Phys. Chem. Chem. Phys., 2022, 24, 12383 (year - 2022) https://doi.org/10.1039/D2CP01089E

23. Troyan I.A., Semenok D.V., Ivanova A.G., Kvashnin A.G., Zhou D., Sadakov A.B., Sobolevskiy O.A., Pudalov B.M. Lyubutin I.S., Oganov A.R. Высокотемпературная сверхпроводимость в гидридах Успехи Физических Наук, УФН 192 799–813 (2022) (year - 2022) https://doi.org/10.3367/UFNr.2021.05.039187

24. Wang Y., Bykov M., Chepkasov I., Samtsevich A., Bykova E., Zhang X., Jiang S-q., Greenberg E., Chariton S., Prakapenka V.B., Oganov A.R., Goncharov A.F. Stabilization of hexazine rings in potassium polynitride at high pressure Nature Chemistry, Nature Chemistry volume 14, pages794–800 (2022) (year - 2022) https://doi.org/10.1038/s41557-022-00925-0

25. Xie C., Tudi A., Oganov A.R. PNO: a promising deep-UV nonlinear optical material with the largest second harmonic generation effect Chemical Communications, Chem. Commun., 2022,58, 12491-12494 (year - 2022) https://doi.org/10.1039/D2CC02364D

26. Lilia B., Hennig R., Hirschfeld P., ..., Romanin D., Daghero D., Valenti R. The 2021 room-temperature superconductivity roadmap Journal of Physics: Condensed Matter, J. Phys.: Condens. Matter 34 (2022) 183002 (51pp) (year - 2022) https://doi.org/10.1088/1361-648X/ac2864

Annotation of the results obtained in 2019
This project focuses on the development and application of novel computational methods/codes for materials discovery. Regarding novel methods/codes, we focused on two central problems: (1) crystal structure prediction (where we extended our method/code USPEX to non-zero temperatures, including full account for lattice anharmonicity; to magnetic structures; and accelerated calculations thanks to new variation operators and to the use of machine learning interatomic potentials) and (2) modelling of strongly correlated systems, including transition metal compounds and electrides (for modelling these systems we use our Amulet code, in which within this project we implemented charge self-consistency). For example, we have formulated a general two- and three-body potential (GTTP) based on machine learning, which was successfully applied to the study of grain boundaries in polycrystalline tungsten, yielding much better accuracy than traditional embedded atom models. Our new machine learning potentials have been implemented by us in the new version of the LAMPPS code. We have shown that electron correlations play an important role in electrides, and developed a microscopic model based on an effective Hamiltonian in Wannier functions basis, enabling detailed understanding of the physics of these compounds. Electrides are an exotic and insufficiently studied class of materials, in which interstitial electron density concentrations behave like anions, leading to unusual properties (e.g. catalytic activity). For electrides Ca2N and Y2C electron correlations lead to an experimentally observed effective mass enhancement (2,4-2,8*m_e). Calculations of local spin susceptibility in Ca2N show nonzero local moments on electride states, and temperature dependence of the uniform magnetic susceptibility indicate low-temperature magnetic ordering. We showed that even in such a simple system as elemental Ca (where under pressure, an electride phase is formed) the sequence of phases under pressure can be explained only when electron correlations are taken into account. For ordered L10 phase of FeNi (tetrathenite), a promising permanent rare-earth-free ferromagnet, preliminary calculations indicate strong correlation effects. Calculated self-energy for 3d-states of Fe, unlike 3d-states of Ni, does not display a Fermi liquid behavior, and spin-spin correlation function indicates well-localized magnetic moments on Fe atoms, whereas the degree of moment localization on Ni is much smaller, demonstrating a more itinerant character of magnetism. Theoretically and experimentally we have shown that elements, not forming stable bulk compounds, can form stable surface compounds – for example, Cu and B form a surface boride Cu8B14. This significantly increases the palette of novel materials, for example, of novel catalysts based on nanomaterials having compositions unachievable for bulk compounds. Using the newly developed method for predicting stable nanoparticles/molecules, we have shown stability of boron nanoparticles Bn with even numbers of boron atoms, while for hydrocarbon molecules C-H the previously known “strange” stability of magnetic hydrocarbon C13H9 was explained. Generally, we find that low-dimensional materials can have unexpected chemical compositions (for example, 2D-compound Cu8B14, remarkable because Cu and B do not form bulk compounds) and unexpected magnetism (e.g., some low-energy 2D-forms of boron are magnetic) - this significantly broadens the palette of materials that can be created. Within this project, we have developed improved models of the hardness and fracture toughness – key mechanical properties. These models (unlike previous ones) correctly predict properties of auxetic materials (materials with negative Poisson ratio). Searching for materials with high hardness and fracture toughness, we at TiB2, CrB4, WB5, and ReB2 possess a particularly appealing combination of these properties. Important results have been obtained for high-Tc superconducting hydrides. In particular, previously predicted by us high-Tc superconductor ThH10 was synthesized under high pressure, and was proved as a superconductor with Tc= 161 К; we also synthesized ThH9 with Tc=146 K, and these are among the highest-Tc superconductors. Even higher-Tc superconductivity was experimentally achieved by us for YH6 – which has Тс=224 К, and we studied this compound both theoretically and experimentally. Finally, a link has been found between superconductivity of metal hydrides with the position of the hydride-forming metal in Mendeleev’s Periodic Table. This will simplify the search for novel high-Tc superconductors – e.g. in ternary hydrides.

Publications

1. Allahyari Z., Oganov A.R. Nonempirical definition of Mendeleev numbers: organizing the chemical space Scienitifc Reports, - (year - 2020)

2. Allahyari Z., Oganov A.R. Coevolutionary search for optimal materials in the space of all possible compounds. NPJ Computational Materials, - (year - 2020)

3. Dong X., Hou J., Kong J., Cui H., Li Y., Oganov A.R., Li K., Zheng H., Zhou X.-F., Wang H.-T. Predicted lithium oxide compounds and superconducting low-pressure Physical Review B, 100, 14, 144104 (year - 2019) https://doi.org/10.1103/PhysRevB.100.144104

4. Koshkaki S.R., Allahyari Z., Oganov A.R., Solozhenko V.L., Tikhonov E.V., Blinov I.V., Qian G.-R., Polovov I.B., Maksimtsev K.V., Mukhamadeev A.S., Chulkin A.V., Korolev A.V., Mushnikov N.V., Li H. Computational prediction of new magnetic materials. NPJ Computational Materials, - (year - 2020)

5. Kvashnin A.G., Allahyari Z., Oganov A.R. Computational discovery of hard and superhard materials Journal of Applied Physics, 126, 4, 040901 (year - 2019) https://doi.org/10.1063/1.5109782

6. Matsko N. Formation of normal surface plasmon modes in small sodium nanoparticles. Physical Review B, - (year - 2020)

7. Mazhnik E, Oganov A.R. A model of hardness and fracture toughness of solids Journal of Applied Physics, 126,12, 125109 (year - 2019) https://doi.org/10.1063/1.5113622

8. Naumova A.S., Lepeshkin S.V., Oganov A.R. Hydrocarbons under pressure: phase diagrams and surprising new compounds in the C-H system Journal of Physical Chemistry С, 123, 33, 20497-20501 (year - 2019) https://doi.org/10.1021/acs.jpcc.9b01353

9. Novoselov D.Y., Korotin D.M., Shorikov A.O., Oganov A.R., Anisimov V.I. Interplay between the Coulomb interaction and hybridization in Ca and anomalous pressure dependence of the resistivity JETP Letters, 109, 6, 387-391 (year - 2019) https://doi.org/10.1134/S0021364019060043

10. Novoselov D.Y., Korotin D.M., Shorikov A.O., Oganov A.R., Anisimov V.I. Weak Coulomb correlations stabilize the electride high-pressure phase of elemental calcium Scientific Reports, - (year - 2020)

11. Pozdnyakov S., Oganov A.R., Mazitov A., Frolov T., Kruglov I., Mazhnik E. Fast general two- and three-body interatomic potential NPJ Computational Materials, готовится к отправке в редакцию (year - 2020)

12. Semenok D.V., Kruglov I.A., Savkin I.A., Kvashnin A.G., Oganov A.R. On Distribution of Superconductivity in Metal Hydrides Current Opinion in Solid State and Materials Science, - (year - 2020)

13. Semenok D.V., Kvashnin A.G., Ivanova A.G., Svitlyk V., Fominski V.Yu., Sadakov A.V., Sobolevskiy O.A., Pudalov V.M., Troyan I.A., Oganov A.R. Superconductivity at 161 K in thorium hydride ThH10: synthesis and properties Materials Today, - (year - 2019)

14. Troyan I.A., Semenok D.V., Kvashnin A.G., Ivanova A.G., Prakapenka V.B., Greenberg E., Gavriliuk A.G., Lyubutin I.S., Struzhkin V.V., Oganov A.R. Synthesis and Superconductivity of Yttrium Hexahydride 𝐼𝑚3̅𝑚-YH6 . Nature Physics, - (year - 2020)

15. Yue C., Weng X.-J., Gao G., Oganov A.R., Dong X., Shao X., Wang X., Sun J., Xu B., Wang H.-T., Zhou X.-F., Tian Y. Discovery of copper boride on Cu(111) Nature Communications, - (year - 2020)

16. Zhang J., McMahon J.M., Oganov A.R., Li X., Dong H., Wang S. High-temperature superconductivity in the Ti-H system at high pressures. Physical Review B, - (year - 2020)

17. Zhou D., Semenok D.V., Duan D., Xie H., Chen W., Huang X., Li X., Liu B., Oganov A.R., Cui T. Superconducting praseodymium superhydrides Science Advances, - (year - 2019)

18. Zhu M.H., Weng X.J., Gao G., Dong S., Ling L.F., Wang W.H., Zhu Q., Oganov A.R., Dong X., Tian Y.J., Zhou X.F., Wang H.T. Magnetic borophenes from an evolutionary search PHYSICAL REVIEW B, 99, 20, 205412 (year - 2019) https://doi.org/10.1103/PhysRevB.99.205412

19. Oganov A.R., Pickard C.J., Zhu Q., Needs R.J. Structure prediction drives materials discovery Nature Reviews Materials, 4,5, 331-348 (year - 2019) https://doi.org/10.1038/s41578-019-0101-8

20. - Получен рекордный ториевый сверхпроводник Индикатор, статья от 7.11.2019 (year - )

21. - Ученые сделали модель описания твердости материалов более универсальной Индикатор, статья от 14.10.2019 (year - )

22. - Предсказанный в прошлом году высокотемпературный сверхпроводник успешно синтезирован Полит.ру, статья от 8.11.2019 (year - )

23. - Победитель победита N+1, статья от 30.09.2019 (year - )

24. - Thorium Superconductivity: New High-Temperature Superconductor Discovered Sci. Tech. Daily, статья от 8.11.2019 (year - )

Annotation of the results obtained in 2020
This project has lead to a number of very important results and methodological developments for computational materials science. Let us highlight the following results: 1. Methodology: acceleration of USPEX algorithm due to new variation operators and improved structure generators. New version of USPEX was published; we also organized an online USPEX workshop (>250 registered participants). USPEX was extended to predict stable crystal structures at finite temperatures (this necessitated the development of a way to calculate free energies accurately and quickly). We have developed a technique for rapid evaluation of thermoelectric properties (this was implemented in the new version of our AICON code). In our AMULET code we implemented charge self-consistency for DFT+DMFT method. A machine learning model for rapid calculation of the mechanical properties (bulk and shear moduli, hardness, fracture toughness) was developed. We have published a paper reporting a new method – Mendelevian Search – allowing one to predict materials with desired properties, among all possible compounds. This necessitated the formulation of the “chemical space” in terms of so called Mendeleev numbers. Mendeleev numbers, introduced by D. Pettifor and refined by us, arrange the elements in a sequence such that variation of properties along the sequence is smoothest. 2. Theoretical predictions of new high-temperature superconductors were made and confirmed experimentally for a number of compounds, such as: ThH10 (experiment gives critical temperature of superconductivity Тс = 161 К), YH6 (experimental Тс = 224 К), (Y,La)H6 (experimental Тс = 253 К). We have found a close link between Tc of a hydride and the position of a hydride-forming element in the Periodic Table. 3. Theoretical prediction and experimental synthesis of new exotic hydrides forming under pressure: PrH9, NdH7, NdH9, Eu8H46, EuH9, BaH12, CeH9. We predicted theoretically new high-Tc superconducting hydrides Ti2H13 and TiH22 (Tc up to 150 К), LaH16 (Tc up to 156 К). 4. We established that diamond (and hexagonal diamond, lonsdaleite) is the hardest possible substance. 5. Studying the С-H-N-O system at high pressures and temperatures we showed that at P-T-conditions of the interiors of Neptune and Uranus (and their expected chemical compositions) diamond formation is favorable. We have described major chemical changes occurring at these extreme conditions, with the formation of new kinds of molecules and ions. 6. We have theoretically predicted and experimentally confirmed the formation of a new pseudohexagonal 2D-phase of NaCl on diamond substrate. 7. We have established that strong electronic localization in electrides can lead to important effects of strong electron correlation. For example, Mott transition insulator-metal in beta-Yb5Sb3 takes place entirely on electride states. We have reproduced phase transitions in Ca, inaccessible to one-particle theories. We have predicted strong antiferromagnetic fluctuations in 2D-electride Ca2N and 0D-electride beta-Yb5Sb3. It was shown that localized magnetic moments in voids of beta-Yb5Sb3 have long lifetimes. 8. We have predicted hitherto unknown copper fluorides Cu2F5, CuF3. These compounds, stable at normal pressure, are strongly correlated charge-transfer insulators. Careful comparison of their electronic structure with that of high-Tc superconductor La2CuO4 led us to suggest that doped CuF3 and Cu2F5 may display high-Tc superconductivity of the same type as cuprates. 9. We have predicted stable and low-energy metastable cocrystals of high-energy-density molecules – such as HMX:CL-20. Cocrystals of this kind may possess low sensitivity (i.e. higher safety) while having very high caloricity. 10. 19 papers were published in high-level (mostly Q1) international scientific journals; another 3 papers were accepted for publication.

Publications

1. Allahyari Z., Oganov A.R. Nonempirical definition of Mendeleev numbers: organizing the chemical space Physical Chemistry, том 124, стр. 23867-23878 (year - 2020)

2. Allahyari Z., Oganov A.R. Coevolutionary search for optimal materials in the space of all possible compounds npj Computational Materials, volume 6, article number: 55 (year - 2020) https://doi.org/10.1038/s41524-020-0322-9

3. D. Zhou, D.V. Semenok, D. Duan, H. Xie, W. Chen, X. Huang, X. Li, B. Liu, A.R. Oganov, T. Cui Superconducting praseodymium superhydrides Science Advances, 6, 9, eaax6849 (year - 2020) https://doi.org/10.1126/sciadv.aax6849

4. D. Zhou, D.V. Semenok, H. Xie, X. Huang, D. Duan, A. Aperis, P. M. Oppeneer, M. Galasso, A.I. Kartsev, A.G. Kvashnin, A.R. Oganov, T.Cui High-Pressure Synthesis of Magnetic Neodymium Polyhydrides Journal of American Chemical Society, 142, 6, 2803–2811 (year - 2020) https://doi.org/10.1021/jacs.9b10439

5. D.V. Semenok, A.G. Kvashnin, A.G. Ivanova, V. Svitlyk, V.Yu. Fominski, A.V. Sadakov, O.A. Sobolevskiy, V.M. Pudalov, I.A. Troyan, A.R. Oganov Superconductivity at 161K in thorium hydride ThH10: Synthesis and properties Materials Today, 33, 36-44 (year - 2020) https://doi.org/10.1016/j.mattod.2019.10.005

6. D.V. Semenok, I.A. Kruglov, I.A. Savkin, A.G. Kvashnin, A.R. Oganov On Distribution of Superconductivity in Metal Hydrides Current Opinion in Solid State and Materials Science, 24, 2, 100808 (year - 2020) https://doi.org/10.1016/j.cossms.2020.100808

7. Dmitrii V. Semenok, Di Zhou, Alexander G. Kvashnin, Xiaoli Huang, Michele Galasso, Ivan A. Kruglov, Anna G. Ivanova, Alexander G. Gavriliuk, Wuhao Chen, Nikolay V. Tkachenko, Alexander I. Boldyrev, Ivan Troyan, Artem R. Oganov, and Tian Cui Novel Strongly Correlated Europium Superhydrides Journal of Physical Chemistry Letters, 12,32-40 (year - 2021) https://doi.org/10.1021/acs.jpclett.0c03331

8. Kruglov I.A., Semenok D.V., Song H., Szczesniak R., Wrona I.A., Akashi R., Davari Esfahani M.M., Duan D., Cui T., Kvashnin A.G., Oganov A.R. Superconductivity of LaH10 and LaH16 polyhydrides Phys. Rev. B., 101, 024508 (year - 2020) https://doi.org/10.1103/PhysRevB.101.024508

9. Kvashnin A.G., Tantardini C., Zakaryan H.A., Kvashnina Yu.A., Oganov A.R. Computational search for new W-Mo-B compounds Chemistry of Materials, 32, 16, 7028–7035 (year - 2020) https://doi.org/10.1021/acs.chemmater.0c02440

10. Mazhnik E., Oganov A.R. Application of machine learning methods for predicting new superhard materials Journal of Applied Physics, - (year - 2020) https://doi.org/10.1063/5.0012055

11. Miao N., Wang J., Gong Y., Wu J., Niu H., Wang S., Li K., Oganov A.R., Tada T., Hosono H. Computational prediction of boron-based MAX phases and MXene derivatives Chemistry of Materials, 32, 16, 6947-6957 (year - 2020) https://doi.org/10.1021/acs.chemmater.0c02139

12. Novoselov D., Korotin D., Shorikov A.O., Oganov A.R., Anisimov V.I. Weak Coulomb correlations stabilize the electride high-pressure phase of elemental calcium J. Phys.: Cond. Matt., 32 445501 (year - 2020) https://doi.org/10.1088/1361-648X/ab99ed

13. Pakhnova M, Kruglov I.,Yanilkin A.,Oganov A.R/ Search for stable cocrystals of energetic materials using the evolutionary algorithm USPEX Royal Society of Chemistry, том 22, стр 16822-16830 (year - 2020) https://doi.org/10.1039/d0cp03042b

14. Shorikov A.O., Skornyakov S.L., Anisimov V.I., Oganov A.R. Electronic correlations in uranium hydride UH5 under pressure Phys.-Cond. Matt., - (year - 2020) https://doi.org/10.1088/1361-648X/ab95cb

15. Tikhomirova K.A., Tantardini C., Sukhanova E.V., Popov Z.I., Evlashin S.A., Tarkhov M.A., Zhdanov V.L., Dudin A.A., Oganov A.R., Kvashnin D.G., Kvashnin A.G. Exotic two-dimensional structure: the first case of hexagonal NaCl Journal of Physical Chemistry Letters, - (year - 2020) https://doi.org/10.1021/acs.jpclett.0c00874

16. Wuhao Chen, Dmitrii V. Semenok, Alexander G. Kvashnin, Xiaoli Huang, Ivan A. Kruglov, Michele Galasso, Hao Song, Defang Duan, Alexander F. Goncharov, Vitali B. Prakapenka, Artem R. Oganov & Tian Cui Synthesis of molecular metallic barium superhydride: pseudocubic BaH12 Nature Communications, - (year - 2020) https://doi.org/10.1038/s41467-020-20103-5

17. Zhang J., McMahon J.M., Oganov A.R., Li X.F., Dong X., Dong H.F., Wang S.N. High- temperature superconductivity in the Ti-H system at high pressures Phys. Rev. B, B101, 134108 (year - 2020) https://doi.org/10.1103/PhysRevB.101.134108

18. Zhou D., Semenok D.V., Duan D., Xie H., Chen W., Huang X., Li X., Liu B., Oganov A.R., Cui T. Superconducting praseodymium superhydrides Science Advances, Vol. 6, no. 9, eaax6849 (year - 2020) https://doi.org/10.1126/sciadv.aax6849

19. Zhou D., Semenok D.V., Xie H., Huang X., Duan D., Aperis A., Openeer P.M., Galasso M., Kartsev A.I., Kvashnin A.G., Oganov A.R., Cui T. High-pressure synthesis of magnetic neodymium superhydrides J. Am. Chem. Soc., V. 142, P. 2803−2811 (year - 2020) https://doi.org/10.1021/jacs.9b10439

20. - Российские ученые создали метод картирования химического пространства gazeta.ru, 05/11/2020 (year - )

21. - Российские химики научились предсказывать материалы с любыми свойствами ТАСС Наука, 14/05/2020 (year - )

22. - Новый алгоритм выбирает лучшие материалы из бесконечного множества Популярная Механика, 14/05/2020 (year - )

23. - В России создан «невозможный» материал для новых сверхпроводников CNews, 04/03/2020 (year - )

Annotation of the results obtained in 2021
The aim of our project is to develop a new generation of methods for computational materials discovery. Based on the earlier developed USPEX method for crystals structure prediction, we have developed the coevolutionary method COPEX, capable of reliably and efficiently predicting stable compounds in very complex multicomponent systems. The USPEX code was rewritten in a new, modular, architecture, and its two new versions have been published. Prediction of stable structures and compositions has been enabled at finite temperatures – for this, we had to develop a fast and accurate technique for calculating the entropies and free energies. We also made a significant progress in developing new techniques and codes for calculating materials properties – we created AICON code for calculating thermoelectric properties and thermal conductivities and Automag code for predicting magnetic structures and properties. We have also enabled prediction of compositions and structures of thin films on a substrate, and found that in thin films new compounds may appear, which do not exist in the bulk form – such as Cu4B7, found by our theoretical and experimental work. In strongly correlated systems, such as NiO, the surface of the crystal can have a significantly different electronic structure compared to the bulk. We have reappraised electronegativity, a very important chemical property of atoms, and developed a new electronegativity scale. We have developed a new formalism and a machine learning model for predicting tensorial properties, and applied them to mechanical properties. Major successes were scored in the field of high-temperature superconductivity – a number of unique superconductors with Tc up to 253 K were predicted and then studied experimentally and theoretically. A new phase of KN3 with hexazine rings was discovered and studied experimentally and theoretically – this should be a high energy density material. Using USPEX we explored the chemistry of the C-H-N-O system (dominating the chemistry of planets Uranus and Neptune), and found inevitability of the formation of diamond in the interiors of these planets – earlier, this process was linked with excess heat flux from Neptune’s surface. In 2021 we have also obtained a number of interesting results for materials for non-linear optics, magnets and electides. We have also predicted a number of potentially effective thermoelectric materials, which are now being explored by our experimental collaborators.

Publications

1. Boeri L., Hennig R.G., Hirschfeld P.J., Profeta G., Sanna A., Zurek E., Pickett W.E., Amsler M., Dias R., Eremets M., Heil C., Hemley R.J., Liu H., Ma Y., Pierleoni C., Kolmogorov A., Rybin N., Novoselov D., Anisimov V.I., Oganov A.R... The 2021 room-temperature superconductivity roadmap Journal of Physics: Condensed Matter, 2021,33 (year - 2021) https://doi.org/10.1088/1361-648X/ac2864

2. Fan T., Oganov A.R. AICON2: A program for calculating transport properties quickly and accurately Computer Physics Communications, 2021, 266,108027. (year - 2021) https://doi.org/10.1016/j.cpc.2021.108027

3. Fan T., Oganov A.R. Discovery of high performance thermoelectric chalcogenides through first-principles high-throughput screening Journal of Materials Chemistry C, 2021,9, 13226-13235 (year - 2021) https://doi.org/10.1039/D1TC03146E

4. Leonov I., Biermann S. Electronic correlations at paramagnetic (001) and (110) NiO surfaces: Charge-transfer and Mott-Hubbard-type gaps at the surface and subsurface of (110) NiO Physical Review B, 2021, 103, 165108 (year - 2021) https://doi.org/10.1103/PhysRevB.103.165108

5. Li H., Min J., Yang Z., Wang Z., Pan S., Oganov A.R. Prediction of Novel van der Waals Boron Oxides with Superior Deep-Ultraviolet Nonlinear Optical Performance Angewandte Chemie - International Edition, 2021, 60, 19, 10791-10797 (year - 2021) https://doi.org/10.1002/anie.202015622

6. Li K., Wang J., Blatov V.A., Gong Y., Umezawa N., Tada T., Hosono H., Oganov A.R. Crystal and electronic structure engineering of tin monoxide by external pressure Journal of Advanced Ceramics, 2021, 10, 565–577 (year - 2021) https://doi.org/10.1007/s40145-021-0458-1

7. Li X., Niu H., Oganov A.R. COPEX: co-evolutionary crystal structure prediction algorithm for complex systems npj computational materials, 2021, 7,1 ,1-11 (year - 2021) https://doi.org/10.1038/s41524-021-00668-5

8. Naumova A.S., Lepeshkin S.V., Bushlanov P.V., Oganov A.R. Unusual chemistry of the C-H-N-O system under pressure and implications for giant planets Journal of Physical Chemistry A, 2021, 125, 18, 3936–3942 (year - 2021) https://doi.org/10.1021/acs.jpca.1c00591

9. Novoselov D.Y., Anisimov V.I., Oganov A.R. Strong electronic correlations in interstitial magnetic centers of zero-dimensional electride β-Yb5Sb3 PHYSICAL REVIEW B, 2021, 103, 235126 (year - 2021) https://doi.org/10.1103/PhysRevB.103.235126

10. Novoselov D.Y., Korotin D.M., Shorikov A.O., Anisimov V.I., Oganov A.R. Interacting electrons in two-dimensional electride Ca2N Journal of Physical Chemistry C, 2021, 125, 28, 15724-15729 (year - 2021) https://doi.org/10.1021/acs.jpcc.1c04485

11. Rybin N., Novoselov D.Y., Korotin D.M, Anisimov V.I., Oganov A.R. Novel copper fluoride analogs of cuprates Physical Chemistry Chemical Physics, 2021,23,30,5989-15993 (year - 2021) https://doi.org/10.1039/D1CP00657F

12. Semenok D.V., Troyan I.A., Ivanova A.G., Kvashnin A.G., ... Oganov A.R. Superconductivity at 253 K in lanthanum–yttrium ternary hydrides Materials Today, 2021, 48, 18-28 (year - 2021) https://doi.org/10.1016/j.mattod.2021.03.025

13. Tantardini C., Kvashnin A.G., Gatti C., Yakobson B.I., Gonze X. Computational Modeling of 2D Materials under High Pressure and Their Chemical Bonding: Silicene as Possible Field-Effect Transistor ACS Nano, 2021, 15, 4, 6861–6871 (year - 2021) https://doi.org/10.1021/acsnano.0c10609

14. Tantardini C., Oganov A.R. Thermochemical electronegativities of the elements Nature Communications, 2021, 12, 1, 1-9. (year - 2021) https://doi.org/10.1038/s41467-021-22429-0

15. Troyan I.A., Semenok D.V., Kvashnin A.G., Sadakov A.V.,....Oganov A.R. Anomalous high-temperature superconductivity in YH6 Advanced Materials, 2021, 33, 15, 2006832 (year - 2021) https://doi.org/10.1002/adma.202006832

16. Wang Y., Bykov M., Chepkasov I., Samtsevich A.I., Bykova E., Zhang X., Jiang S., Greenberg E., Chariton S., Prakapenka V.B., Oganov A.R., Goncharov A.F. Stabilization of hexazine rings in potassium polynitride at high pressure nature chemistry, - (year - 2022)

17. Yue C., Weng X.-J., Gao G., Oganov A.R., Dong X., Shao X., Wang X., Sun J., Xu B., Wang H.-T., Zhou X.-F., Tian Y. Formation of copper boride on Cu(111) Fundamental Research, 2021, 1, 4, 482-487 (year - 2021) https://doi.org/10.1016/j.fmre.2021.05.003