199 research outputs found
Impact of lattice vibrations on equation of state of the hardest boron phase
Get PDFAn accurate equation of state (EOS) is determined for the high-pressure orthorhombic phase of boron, B(28), experimentally as well as from ab initio calculations. The unique feature of our experiment is that it is carried out on the single crystal of B(28). In theory, we take into consideration the lattice vibrations, often neglected in first-principles simulations. We show that the phonon contribution has a profound effect on the EOS of B(28), giving rise to anomalously low values of the pressure derivative of the bulk modulus and greatly improving the agreement between theory and experiment.Original Publication:Eyvas Isaev, Sergey Simak, Arkady Mikhaylushkin, Yu. Kh. Vekilov, E. Yu. Zarechnaya, L. Dubrovinsky, N. Dubrovinskaia, M. Merlini, M. Hanfland and Igor Abrikosov, Impact of lattice vibrations on equation of state of the hardest boron phase, 2011, Physical Review B. Condensed Matter and Materials Physics, (83), 13, 132106.http://dx.doi.org/10.1103/PhysRevB.83.132106Copyright: American Physical Societyhttp://www.aps.org
Metastability of fcc-related Si-N phases
No full textThe phenomenon of superhardening in TiN/SiNx nanocomposites and the prediction of extreme hardness in bulk gamma-Si3N4 have attracted a large interest to this material system. Attempts to explain the experimental findings by means of first-principles calculations have so far been limited to static calculations. The dynamical stability of suggested structures of the SiNx tissue phase critical for the understanding of the nanocomposites is thus unknown. Here, we present a theoretical study of the phonon-dispersion relations of B1 and B3 SiN. We show that both phases previously considered as metastable are dynamically unstable. Instead, two pseudo-B3 Si3N4 phases derived from a L1(2)- or D0(22)-type distribution of Si vacancies are dynamically stable and might explain recent experimental findings of epitaxial SiNx in TiN/SiNx multilayers.Original Publication:Björn Alling, Eyvas Isaev, Axel Flink, Lars Hultman and Igor Abrikosov , Metastability of fcc-related Si-N phases, 2008, Physical Review B. Condensed Matter and Materials Physics, (78), 13, 132103.http://dx.doi.org/10.1103/PhysRevB.78.132103Copyright: American Physical Societyhttp://www.aps.org
Single-monolayer SiNx embedded in TiN : A first-principles study
Get PDFThe dynamical and thermodynamic stability of a single monolayer of SiNx sandwiched isostructurally between B1-TiN(001) and (111) oriented slabs are investigated by means of density functional theory. Possible dynamical stabilization of the (001) interface, by distortion of the Si-N bonds, is considered and found to almost, but not completely, remove the phonon instabilities. The (111) interface on the other hand is found to be dynamically stable. We furthermore relax the stoichiometry degree of freedom by allowing for Si vacancies in the lattice and show that the ideal 1:1 SiN stoichiometry in both interfaces are thermodynamically unstable with respect to Si vacancy formation regardless if the system is grown under nitrogen-rich or nitrogen-poor conditions, and therefore ruling out its relevance for performance of real materials.Original Publication:Tobias Marten, Eyvas Isaev, Björn Alling, Lars Hultman and Igor Abrikosov, Single-monolayer SiNx embedded in TiN: A first-principles study, 2010, Physical Review B. Condensed Matter and Materials Physics, (81), 21, 212102.http://dx.doi.org/10.1103/PhysRevB.81.212102Copyright: American Physical Societyhttp://www.aps.org
LASERCOOLED RaF AS A LABORATORY FOR TESTING FUNDAMENTAL SYMMETRIES
No full textAuthor Institution: Clemens-Schopf Institute, Technical University of Darmstadt, 64287 Darmstadt, GermanyModern spectroscopical methods allow to reach an accuracy in measurements of molecular spectra that is sufficient for testing symmetry violation in fundamental weak interactions. As was demonstrated in recent experimental search for a permanent electric dipole moment of the electron in YbF [1] and PbO [2], diatomic molecules with an open electronic shell present extremely powerful instrument to study violations of space parity (-odd) and space parity and time reversal (-odd) symmetries. In this talk we discuss the enhancement of -odd and -odd effects in diatomic molecules and consider some prospective candidates for carrying out successful measurements. Radium monofluoride is shown to be a very prospective molecular candidate for observing possible symmetry violations due to its predicted suitability to direct laser cooling [3], large enhancement factors (both electronic and nuclear) [4] and efficient (for the given class of molecules) production route. \\~ REFERENCES: \begin{enumerate} \item J. J. Hudson, D. M. Kara, I. J. Smallman, B. E. Sauer, M. R. Tarbutt and E. A. Hinds, Nature, 473 (2011) \item S. Eckel, P. Hamilton, E. Kirilov, H.W. Smith and D. DeMille, http://arxiv.org/abs/1303.3075v1 \item T. A. Isaev, S. Hoekstra and R. Berger, Phys.Rev.A, 82, 5, 2010 \item T. A. Isaev and R. Berger, http://arxiv.org/abs/1302.5682 \end{enumerate
«ВЕРОЯТНОСТНЫЙ ПРОЦЕСС ПОЗНАНИЯ»
Get PDFAbout the book: Igor P. Isaev as a researcher and professor./Composed by V.I. Isaev and Yu.Yu.Chuverin.– Moscow, Moscow State University of Railway Engineering publ., 2011.– 128 pp.The book is dedicated to the memory of Igor P. Isaev, well-known scientist and researcher in the sphere of railway transport, D.Sc. (Tech), meritorious scientist of Russia, professor emeritus of Moscow State University of Railway Engineering (MIIT). The book contains the biography of I. Isaev, the life history of his family, reviews of his oeuvres, brief memoirs of his colleagues and pupils.Игорь Петрович Исаев – ученый и учитель/Составители В. И. Исаев, Ю. Ю. Чуверин. – М.: МИИТ, 2011. – 128 с.Книга посвящена памяти известного ученого, специалиста в области железнодорожного транспорта, заслуженного деятеля науки и техники России, доктора технических наук, почетного профессора МИИТ. В сборнике представлены биографические материалы об Игоре Исаеве и его семье, обзоры научных работ, воспоминания коллег и учеников. Сугубо документальный жанр помогает читателю по достоинству оценить исследовательский и педагогический талант человека, фронтовой и жизненный опыт, редкая интеллигентность которого снискали ему уважение, признательность и благодарность товарищей по профессии, студентов, людей самых разных интересов и взглядов
Dynamic stability of palladium hydride: An ab initio study
Get PDFWe present results of our ab initio studies of electronic and dynamic properties of ideal palladium hydride PdH and its vacancy ordered defect phase Pd(3)VacH(4) ("Vac" - vacancy on palladium site) with L1(2) crystal structure found experimentally and studied theoretically. Quantum and thermodynamic properties of these hydrides, such as phonon dispersion relations and the vacancy formation enthalpies have been studied. Dynamic stability of the defect phase Pd(3)VacH(4) with respect to different site occupation of hydrogen atoms at the equilibrium state and under pressure was analyzed. It was shown that positions of hydrogen atoms in the defect phase strongly affect its stability and may be a reason for further phase transitions in the defect phase.Original Publication:L E Isaeva, D I Bazhanov, Eyvas Isaev, S V Eremeev, S E Kulkova and Igor Abrikosov, Dynamic stability of palladium hydride: An ab initio study, 2011, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, (36), 1, 1254-1258.http://dx.doi.org/10.1016/j.ijhydene.2010.06.130Copyright: Elsevier Science B.V., Amsterdam.http://www.elsevier.com
AUTHOR STRATEGIES IN RYURIK IVNEV’S “SUN IN THE COFFIN”. BOOK OF POEMS
No full textThe author’s problem in Ryurik Ivnev’s ‘The Sun in the Coffin’ (1921) is studied from the author’s perspectives. It is concluded that at least three Ryurik Ivnev’s strategies as an author can be distinguished: the first, the least obvious, coming from his youthful excitement about Nadson’s neo-romantic poetry, Baudelaire’s and Blok’s symbolism and appearing in a very weakened form, can be called a decadent one. The second strategy is determined by the poet’s recent belonging to egofuturism. The third one was formed under the influence of imaginism aesthetics, to which the poet was attracted when writing the book. Ryurik Ivnev’s strategies, spontaneously but sometimes consciously, were aimed at forming the literary image of the author, identified with the persona. The themes and motives of the book are concentrated around the hypertrophic and screened in the text «I» which becomes the center of Ryurik Ivnev’s poetic worldview. All the strategies are intricately intertwined and give rise to the quality of the style that distinguishes sharply ‘The Sun in the Coffin’ against the background of the Russian poetry of the 1920s and which can be referred to as surrealism
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