Discovery of novel and unexpected sodium chlorides: Na3Cl, Na2Cl, Na3Cl2, NaCl3, NaCl7
This work challenges traditional chemical concepts: while classical rules of chemistry predict that the only possible stable sodium chloride is NaCl, variable-composition USPEX calculations predict that under moderate pressure numerous new compounds become thermodynamically stable. Most of these are metallic. Some of the predicted compouns are two-dimensional metals. These predictions have been verified by experiments, which synthesized and characterized the predicted compounds. Such "forbidden" compounds are expected to become stable in many other systems under pressure. This work has received huge resonance in professional and lay media, below is a small selection of the press.
- Videolecture Forbidden chemistry (December 2013)
- Videolecture The discovery of forbidden chemistry (January 2014)
- Reformulating table salt, by J. Ibanez Insa, Science, 20 December 2013
- "New sodium chlorides assault chemical rules", Chemistry World, 19 December 2013
- "New Salt Compounds Challenge Foundation of Chemistry", Farsnews, 23 December 2013
- "Upending chemistry's atomic law", The National, 11 January 2014
- "Crystals under pressure", Spectroscopy Now, 1 January 2014
- Russian scientist has discovered impossible compounds, gazeta.ru, 19 December 2013 [in Russian]
- The first findings of new chemistry, gazeta.ru, 20 December 2013 [in Russian]
- Impossible compounds created, Russian Newspaper, 20 December 2013 [in Russian]
- "SBU Team discovers compounds that challenge foundation of chemistry", Press release of Stony Brook University, 19 December 2013
- "Breakthrough - SBU Discovery Challenges the Foundation of Chemistry", SUNY Research Foundation, 12 March 2014
- "Salt shakes up scientific world", Stony Brook University, February 2014
- "Table Salt Experiments Performed under High-Pressure Violate Existing Chemistry Rules",French Tribune, 20 December 2014
- Various news pieces in French, German, Ukrainian, Vietnamese, English
Prediction of low-energy two-dimensional boron structure with massless Dirac fermions and properties superior to graphene
It has been assumed the most stable two-dimensional structure formed by boron atoms is the so called planar alpha-sheet, and on its basis structures of boron nanoparticles and nanotubes have been postulated. Using USPEX, we showed that the alpha-sheet is massively unstable and non-planar structures possess the lowest energies. Among these, one stands out: its electronic structure features distorted Dirac cones, with electronic velocities being in one direction substantially higher than in graphene and substantially lower in the perpendicular direction. The instability of the alpha-sheet and stability of completely different structures calls for a reassessment of structural models of boron nanoparticles and nanotubes, while the electronic structure of the newly discovered 2D-boron structure may lead to practical applications.
- "Boron, discovered in 1808, gets a nanorefresh", Stony Brook University, 4 March 2014
- "Does boron-based graphene exist?", Physics World, 5 February 2014
- "Boron gets a nano refresh: Scientists find stable 2D structures with unique properties", Phys.org, 6 March 2014
- "Boron, discovered in 1808, gets a nano refresh", Science Daily, 4 March 2014
- Scientists doubt the existence of borophene, lenta.ru, 5 February 2014 [in Russian]
Prediction of compounds that defy chemical intuition: Mg3O2 and MgO2
MgO, in the form of ferropericlase (Mg,Fe)O, makes up about 10% of the Earth's volume. Until this work, MgO was believed to be the only thermodynamically stable magnesium oxide. Our work showed that at high pressure new oxides MgO2 and Mg3O2 become stable. These new oxides defy standard chemical intuition and may be planet-forming materials in some planets.
- Geoscientists Predict New Compounds Could Change Our View of What Planets are Made of, press release of Stony Brook University, 23 April 2013
Fate of boranes under pressure
Using USPEX in the variable-composition mode, we show that above 153 GPa all traditional boranes (including BH3) become thermodynamically unstable and BH (first appearing as a stable compound at 30 GPa) is the only stable compound of boron and hydrogen at pressures above 153 GPa. At 168 GPa BH undergoes a semiconductor-metal transition, the elegant mechanism of which is investigated using the newly developed (by us, and implemented in the USPEX code as well) variable-cell NEB method. The high-pressure metallic phase is predicted to be a superconductor with a Tc of 14-21 K at 175 GPa.
Stability of xenon oxides and the "missing xenon paradox"
Xenon is an inert gas, and its oxides, though known, are not stable againt decomposition into elemental xenon and oxygen (some even decompose explosively). Using USPEX, we show that at pressures above 83 GPa stable oxides XeO, XeO2, and XeO3 are formed. We also show that there are no stable silicates of xenon in the same pressure range. Furthermore, xenon oxides can only be formed in extremely oxidative environments and thus cannot exist in the Earth's lower mantle. However, due to acquired reactivity under pressure and the ability to readily form strong Xe-O bonds, we conclude that xenon can be trapped by defects and grain boundaries of mantle minerals.
- SBU Geosciences Professor Predicts Stable Compounds of Oxygen and Inert Gas Xenon , press release of Stony Brook University, 11 November 2012
- Videointerview of Stony Brook University , 22 November 2012
Establishing the structure of an important high energy-density material: Mg(BH4)2
Mg(BH4)2 is a prime candidate for hydrogen storage (e.g. for rocket fuel) and was earlier found to undergo a phase transition at 1-2 GPa into the delta-Mg(BH4)2 phase, with a dramatic density increase of >40%. Given its exraordinarily low pressure, this tranition could be used for practical purposes. However, we find that the crystal structure of the delta-phase was incorrectly determined from X-ray powder diffraction by Filinchuk et al. (Angew. Chem. 2011): their structure is energetically unfavorable and dynamically unstable. Using USPEX, we surprisingly found another structure that even better describes experimental X-ray diffraction and is much more stable. We have found not only the structure of the delta-phase, but also that of the elusive delta'-phase. This example shows the danger of relying solely on experimental data when solving crystal structures from powder data, and the importance of coupling such experiments with advanced theory.
- SBU Geosciences Researchers Re-Establish the Structure of Magnesium Borohydride , press release of Stony Brook University, 13 December 2012
Prediction of the densest carbon allotrope
This work illustrates how USPEX method can be used for optimizing target physical properties – here, we searched for the densest possible carbon allotrope. Diamond is the densest known material (in the sense that there are more atoms per unit volume in diamond than in any other known material). Nevertheless, we find that denser (by up to ~3.2%) phases are possible and have extremely interesting optical (very high refractive indices and dispersion of light) and electronic (band gaps from 3.0 to 7.3 eV) properties.
- Researchers predict densest possible materials, Happenings, 14 June 2011
- Russian scientist Artem Oganov and his foreign colleagues discovered three new forms of carbon, infox.ru, 9 June 2011 [in Russian]
- Chemists simulate a material that will outshine diamond, RIA Novosti, 9 June 2011 [in Russian]
- New super-dense forms of carbon outshine diamond, New Scientist, 8 June 2011
- Three superdense forms of carbon are theoretically predicted, science.compulenta.ru, 8 June 2011 [in Russian]
- Researchers at Stony Brook University Predict Material Denser than Diamond, press release of Stony Brook University, 7 June 2011
Prediction of the structure of graphane
Using USPEX, we showed that for CH the most stable structure is not benzene, but graphane (2D-sheet of the diamond structure, passivated by hydrogen atoms). Graphane was found to have several low-energy isomers. It is surprising that benzene, an archetypal organic molecule known since 1825, is less stable than graphane (discovered only in 2009).
- (Benzene, the) God of organic chemistry, gazeta.ru, 30 March 2011 [in Russian]
High-pressure behavior of methane and its implications for the interiors of planet Neptune
This work clarifies the puzzle of anomalously large heat flux from planet Neptune. An interesting hypothesis was that at high pressures and temperatures methane (CH4), a major component of Neptune (the composition of which can be schematically represented as H2O:CH4:NH3 = 59:33:8), decomposes with the formation of diamond, sinking of which would produce enormous energy. The main uncertainty was whether the decomposition of methane is thermodynamically favorable. Through structure prediction using USPEX, we confirmed that at high pressures and temperatures methane should first polymerize forming ethane+hydrogen (2CH4=C2H6+H2) and then butane+hydrogen (2C2H6=C4H10+H2), and then diamond+hydrogen (C4H10=4C+5H2). This lends strong support to the idea of massive diamond formation in the interior of Neptune. This could also explain the origin of the recently discovered diamond planets.
- Solving the mysteries of Neptune's excessive heat, Research Foundation of SUNY, May 2011
- New Crystal Structure Prediction Method Helps to Unveil Neptune’s Excessive Heat Mystery, azom.com, 7 January 2011
- Breakthrough in Crystal Structure Prediction Supports Theory on Neptune's Interior Heat, press release of Stony Brook University and newswise.com, 5 January 2011
- Scientists develop breakthrough method for crystal structure prediction, physorg.com, 5 January 2011
- USPEX Helps to Solve Long-Standing Mystery of Planet Neptune's Excessive Heat, news of the Research Foundation of Stony Brook University, January 2011
- Skies with diamonds, Popular Mechanics, November 2010 [in Russian]
Study of exotic structures and superconductivity of calcium under pressure
Compressed calcium is the highest-temperature elemental superconductor (Tc = 25 K) and its rich polymorphism is still mysterious both from the experimental and theoretical viewpoints. We have predicted, through global optimization using USPEX, the stability of the beta-Sn-like phase of Ca – and this prediction was recently confirmed. Higher-pressure phases have also been predicted, giving the ab initio (DFT) optimal solution for comparison with experiments.
- Elements Under Pressure, gazeta.ru, 7 April 2010 [in Russian]
- Quantum mechanics managed to predict properties of calcium, RIA Novosti, 5 April 2010 [in Russian]
- Scientists predict exotic behavior of calcium under pressure, Izvestiya, 5 April 2010 [in Russian]
Prediction of stable compounds LiH8, LiH6 and LiH2
High pressure fundamentally changes chemical bonding and can lead to violations of basic rules of chemistry. We have predicted, using USPEX, that at pressures around 100 GPa and above LiH will not be the only stable lithium hydride – LiH2, LiH6 and LiH8 will also be thermodynamically stable.
- Lithium hydrides help studies of metallic hydrogen, www.elementy.ru, 25 November 2009 [in Russian]
- Unexpected Hydrides Become Stable Metals at Pressure Near One Quarter Required to Metalize Pure Hydrogen Alone, physorg.com, 12 October 2009 (based on Press Release of Stony Brook University)
- For Future Superconductors, a Little Bit of Lithium May Do Hydrogen a Lot of Good, nsf.gov, 5 October 2009
Structure of "superhard graphite"
In 1963, Aust and Drickamer have found a new superhard carbon allotrope. It was obtained by room-temperature compression of graphite and confirmed by numerous subsequent experiments, but its structure could not be solved for nearly 50 years. In 2006, Oganov and Glass reported a low-enthalpy structure of carbon found with USPEX as a metastable state, which closely corresponded to the 2x1 reconstruction of diamond (111) surface, but surprisingly was never proposed before as a 3D-structure. In 2009, we (Li et al.) found that this structure, named M-carbon, perfectly matches all observations for this new carbon allotrope. Several other structures were shown to match experiments as well, however. The dispute was resolved by our calculations (Boulfelfel et al., 2012), which found that among all possible structures M-carbon has the lowest barrier of formation from graphite upon room-temperature compression, and is thus the likeliest phase to form. Shortly afterwards, experimentalists from Yale (Wang et al., 2012) found that only M-carbon matches their high-resolution experimental data.
Theoretical/experimental discovery of a transparent high-pressure phase of sodium
In 2008, using USPEX, we made a startling prediction that sodium (a nearly free-electron metal) loses its metallic character under pressure, forming an electride insulator at pressures ~2 Mbar, with a wide band gap that rapidly increases with pressure. This prediction was confirmed by experiment. This prediction was marked as one of the major discoveries ever made by Stony Brook University researchers.
- Scientists have discovered that sodium can be transparent, Chemistry and Life, alhimik.ru, 18 May 2009 [in Russian]
- Transparent sodium, Nature Photonics 3, 250 (2009)
- Transparent sodium, Voice of America, 14 March 2009 [in Russian]
- Solving the crystal maze: the secrets of structure, New Scientist, 16 October 2009
- Sodium: new alchemy, on snob.ru, 26 May 2009 [in Russian]
- A Metal That Becomes Transparent under Pressure, aps.anl.gov, 20 April 2009
- Pressa il sodio e diventerà isolante, Corriere del Ticino, March 2009 [in Italian]
- Fundamental discovery of the physicists may help unravelling the mysteries of giant planets, inauka.ru, worldofscience.ru, 18 March 2009 [in Russian]
- Sous pression, le sodium métallique devient transparent!, futura-sciences.com, 17 March 2009 [in French]
- Transparent sodium, iamik.ru, 17 March 2009 [in Russian]
- Team discovers transparent state of sodium, rdmag.com, 16 March 2009
- Metal Discovered To Become Transparent Under High Pressure, sciencedaily.com, 14 March 2009
- Le Stranezze di Sodio, Corriere del Ticino, 13 March 2009 [in Italian]
- Scientists managed to make sodium transparent, lenta.ru, 13 March 2009 [in Russian]
- High Pressure Makes Sodium Transparent, Softpedia.com, 13 March 2009
- Metal Becomes Transparent Under High Pressure, physorg.com, 12 March 2009
- Team Discovers Metal that Becomes Transparent Under High Pressure, Stony Brook University Press Release, newswise.com, 12 March 2009
- Team Discovers Metal that Becomes Transparent Under High Pressure, lightsources.org, 12 March 2009
- Metal Discovered To Become Transparent Under High Pressure, Science and Technology Updates, March 2009
Theoretical/experimental discovery of a new superhard and partially ionic phase of boron
In 2006, using USPEX, we found the structure of a new stable and superhard boron allotrope, gamma-boron. The paper was published in January 2009 (Oganov et al., Nature 2009) and attracted immediate attention. This discovery was listed as one of the major chemical discoveries of 2009 by Chemistry World (Royal Society of Chemistry). An unusual result was that there is significant charge transfer between different positions of boron atoms (i.e. there is partial ionic character). This result was confirmed by later experimental study (Mondal et al., 2011). Gamma-boron is the hardest known boron allotrope and one of 5-6 hardest solids known to date, as follows from our measurements of its hardness (Solozhenko et al., 2008).
- Material witness: why is boron so hard?, by P. Ball, Nature Materials, 1 January 2010
- Härter als Diamant, Frankfurter Allgemeine Zeitung, 19 November 2009 [in German]
- Boron-based ionic compound, Tribology and Lubrication Technology, May 2009 (with permission from TLT, the monthly magazine published by the Society of Tribologists and Lubrication Engineers).
- Embroidery of boron ions, Chemistry and Life, April 2009 [in Russian]
- Elemental allotropes: boron boride, by N. Withers, Nature Chemistry, 13 February 2009
- Incredibly hard phase of boron, Research Foundation of SUNY, February 2009
- A New Form of the Fifth Element, 2facts.com (subscription-only educational website, highly recommended, pdf-file courtesy of 2facts.com), February 2009
- Big discovery of Artem Oganov, on snob.ru, 13 February 2009 [with a video interview, in Russian]
- New form of boron found, Echo of Moscow, 10 February 2009 [radio program, in Russian]
- High Pressure Yields Novel Single-element Boron 'Compound', Science Daily, 4 February 2009
- Complex Substance from One Element Created, russia-ic.com, 4 February 2009
- High Pressure Yields Novel Single-element Boron 'Compound', chemweb.com, 4 February 2009
- Scientists have synthesized a complex compound made of one element, scienceblog.ru, 3 February 2009 [in Russian]
- Chemists created a compound made of just one element, inauka.ru/izvestiya.ru, 3 February 2009 [in Russian]
- Stupéfiant: le bore forme à lui seul un cristal ionique!, futura-sciences.com, 3 February 2009 [in French]
- New form of boron found, esrf.eu, 3 February 2009
- New form of boron, C&EN News, 2 February 2009
- Theory and Experiment Meet, and a New Form of Boron Is Found, New York Times, 2 February 2009 (click here for a humorous twist)
- Genetic algorithm discovers Boron nearly as hard as diamond, Illinois Genetic Algorithms Laboratory, 2 February 2009
- Discovery of ionic elemental crystal against chemical intuition, chemie.de, 2 February 2009
- Stable form of boron discovered, Science News, 2009
- Discovery of ionic elemental crystal against chemical intuition, ChemEurope, 2 February 2009
- Discovery of ionic elemental crystal against chemical intuition, Chemistry Times, 31 January 2009
- News of chemistry: a new allotrope of boron, chemport.ru, 31 January 2009 [in Russian]
- The many faces of boron, Voice of America, 30 January 2009 [in Russian]
- Superharte Form des Elements Bor entdeckt, Speigel, 30 January 2009 [in German]
- Many faces of boron, Gnews.ua, 30 January 2009 [in Russian]
- Superharte Phase von Bor entdeckt, chemie.de, 30 January 2009 [in German]
- Discovery of ionic elemental crystal against chemical intuition, huliq.com, 30 January 2009
- New phase of elemental boron discovered, ETH Life, 29 January 2009
- Superharte Phase von Bor entdeckt, internetchemie.de, 29 January 2009 [in German]
- Superharte Phase von Bor entdeckt, idw-online.de, 29 January 2009 [in German]
- Amazing: boron alone form a ionic crystal!, 4engr.com, January 2009
- Superharte Phase von Bor entdeckt, idw-online.de, 29 January 2009 [in German]
- Superharte Form des Elements Bor entdeckt, Neue Zurcher Zeitung, 29 January 2009 [in German]
- Stable form of boron discovered, Science News, 2009
- Anything but boring: research finds another form of boron, arstechnica.com, 29 January 2009
- Discovery of ionic elemental crystal against chemical intuition, idw-online.de, 29 January 2009
- Single-element compound is a chemistry first, rdmag.com, 29 January 2009
- First case of an ionic crystal consisting of just one chemical element – boron, labspaces.net, 28 January 2009
- Boro: un elemento dalla doppia personalità, agenziastampa.eu, 28 January 2009 [in Italian]
- Ultra-pure boron structure discovered, Chemistry World, 28 January 2009
- Element of Split Personality, Scientific Frontline, 28 January 2009
- Element of Split Personality - Theoretical And Experimental Studies Find New Superhard Phase Of Boron, Nanotechnology Now, 28 January 2009
- Element of Split Personality - Theoretical And Experimental Studies Find New Superhard Phase Of Boron, Stony Brook University Press Release, 27 January 2009
Prediction of a superconducting state (with Tc=64 K) in germane, GeH4
Using USPEX, we have predicted a high-pressure superconducting phase of germane with an unusually high superconducting Tc of ~64 K.
- Superconductor Week Notes, 23 March 2009
- Un ordinateur pourrait découvrir de nouveaux supraconducteurs, www.futura-sciences.com, 6 January 2009 [in French]
- Crystallographers Use Computers To Find New Superconductor, sciencedaily.com, 1 January 2009
- Crystallographers Use Computers To Find New Superconductor, sciencenewsden.com 2009
- Crystallographers use computers to find a new superconductor, ETH Life, 1 December 2008
- Kristallografen finden am Computer neuen Supraleiter, ETH Life, 1 December 2008 [in German]
Evolutionary methodology for crystal structure prediction
Until 2006, crystal structure prediction was widely thought to be an insoluble problem. This all changed when the USPEX method (Oganov & Glass, 2006; Glass et al., 2006) was developed. Our USPEX code has since been the widest used and the most powerful code in this new field, and most existing codes (XtalOpt, Calypso, Muse) have started from older versions of USPEX. The development of USPEX has been called “revolutionary” (Chaplot & Rao, 2006), as it has opened the new field of computational materials discovery and has led to many fundamental and applied discoveries.
- Breakthrough Method Advances Traditional Chemistry, Laboratory Equipment, 7 January 2011
- Scientists At Stony Brook University Develop Breakthrough Method For Crystal Structure Prediction, press release of Stony Brook University, 5 January 2011
- A chemist applauds an algorithm able to predict crystal structures from chemical composition alone, Nature, 7 June 2007.
- "Computer Endeckt Neue Welten", Spektrum der Wissenschaft, January 2007 [in German]
- "Crystal structure prediction: Evolutionary or Revolutionary Crystallography?", Current Science, 10 December 2006
- "Predicting crystal structures with evolution", Physics Today, September 2006
- "Kristallstrukturen aus dem Computer", Neue Zürcher Zeitung, 5 July 2006 [in German]
- "Crystal clear elements", chemweb.com, 27 June 2006
- "Des simulations prédisent de nouvelles formes d'éléments chimiques", www.techno-science.net, 24 June 2006 [in French]
- "Neue Strukturen der Elemente durch Simulation vorhergesagt", ETH Press Release, 22 June 2006 [in German]
- "Novel forms of the elements predicted by simulation", ETH Press Release, 22 June 2006
- "Elemente unter Druck", www.scienzz.de, 22 June 2006 [in German]
- "Novel forms of the elements predicted by simulation", www.physorg.com, 22 June 2006
- "Down to earth crystal prediction", SpectroscopyNow, 11 January 2006
- "ETH Zürich: Voraussage von Kristallstrukturen dank neuem Simulationsverfahren möglich", chemie.de, 28 December 2005 [in German]
- "New method for simulating crystals: gaining speed", cnews.ru, 23 December 2005 [in Russian]
- "Crystal structure prediction made possible", ETH Press Release, 22 December 2005
- "Crystal structure prediction made possible", Science News Daily, 22 December 2005
- "Crystal structure prediction made possible", physorg.com, 22 December 2005
- "Computer Program Predicts Crystal Structure Quickly and Reliably without Experimental Information", azom.com, 22 December 2005
- "Durchbruch bei Strukturaufklärung", ETH Life, 22 December 2005 [in German]
- "Voraussage von Kristallstrukturen wird möglich", ETH Press Release, 22 December 2005 [in German]
- "Simulation von Kristallen", scienzz.de, 22 December 2005 [in German]
- "Neu entdecktes Mineral im Erdmantel", ETH Press Release, 21 July 2004 [in German]
Polytypes of MgSiO3 and implications for Earth's mantle
Using metadynamics simulations, we show that perovskite and post-perovskite phases of MgSiO3 are related and can be considered as polytypes.
- "Unexpected mechanism of plastic deformation", ETH Press Release, 11 May 2006
- "Crystallographers explain seismic anisotropy of Earth's D" layer", physorg.com, 11 May 2006
Discovery of a new high-pressure phase of alumina, Al2O3
We have predicted that Al2O3 has a high-pressure phase isostructural with MgSiO3 post-perovskite. Increased electrical conductivity observed for Al2O3 at conditions where we predict this phase to be stable suggests that MgSiO3 post-perovskite is likely to be an ionic conductor. High electrical conductivity of post-perovskite D” layer would, by electromagnetic coupling with the Earth’s magnetic field, explain the observed decadal variations of the length of day. These conclusions were confirmed by experimental measurements of Ohta et al. (2008).
Discovery of the post-perovskite phase of MgSiO3
Until 2004, anomalies of the Earth’s D” layer, known since 1950, had no convincing explanation. Guided by experimental insight of Shigeaki Ono, I found that the D” boundary corresponds to a new phase transition of MgSiO3 – from well-known perovskite to the new post-perovskite phase with a CaIrO3-type structure. This prediction was verified by experiments of S. Ono (Oganov & Ono, Nature 2004) and by independent experiments (Murakami et al., Science 2004). Properties of MgSiO3 post-perovskite have explained the anomalous properties – as we showed (Oganov & Ono, 2004), the seismic velocity jumps at the D” boundary, unusually large topography of the D” boundary, seismic anisotropy of this layer and anticorrelations between seismic wave velocities are all quantitatively explained by the post-perovskite transition. This transition also has implications for the Earth’s evolution and probably also for the origin of life.
- "Kernels - pure perovskite", www.gazeta.ru, 21 February 2006 [in Russian]
- "The mantle of attainment", SpectroscopyNow, 1 March 2005
- "New mineral found near the centre of the Earth", sciencewa.net.au, 18 August 2004
- "The core of the matter", worldoil.com, August 2004
- "Neu entdecktes Mineral", planeterde.de, July 2004 [in German]
- "Un nuovo minerale nel mantello terrestre", lescienze.it, 26 July 2004 [in Italian]
- "Tiefe Einsichten", pro-physik.de, 22 July 2004 [in German]
- "Neu entdecktes Mineral im Erdmantel", science.orf.at, 22 July 2004 [in German]
- "Neues Mineral im Erdmantels Entdeckt", Tages Anzeiger, 22 July 2004 [in German]
- "Gegen die Intuition", ETH Life, 22 July 2004 [in German]
- "Neu entdecktes Mineral im Erdmantel", idw-online.de, 21 July 2004 [in German]
- "Newly Discovered Mineral In The Earth’s Mantle", innovations-report.com, 21 July 2004