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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Zaitsev A. I., Molokeev M. S., Aleksandrovsky A. S., Kuzubov A. A., Ignatova N. Y., Kesler V. G.
Заглавие : Electronic structure of α-SrB[[d]]4[[/d]]O[[d]]7[[/d]]: experiment and theory
Место публикации : J. Phys.: Condens. Matter. - 2013. - Vol. 25, no. 8. - Ст.085503. - DOI 10.1088/0953-8984/25/8/085503
Аннотация: The investigation of valence band structure and electronic parameters of constituent element core levels of α-SrB4O7 has been carried out with x-ray photoemission spectroscopy. Optical-quality crystal α-SrB4O7 has been grown by the Czochralski method. Detailed photoemission spectra of the element core levels have been recorded from the powder sample under excitation by nonmonochromatic Al Kα radiation (1486.6 eV). The band structure of α-SrB4O7 has been calculated by ab initio methods and compared to XPS measurements. It has been found that the band structure of α-SrB4O7 is weakly dependent on the Sr-related states.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Makarov I. A., Shneyder E. I.
Заглавие : Quantum phase transitions and superconductivity in single- and two-layer cuprates in the multiband theory of Hubbard fermions
Место публикации : J. Supercond. Nov. Magn. - 2013. - Vol. 26, Is. 8. - P.2607-2609. - ISSN 1557-1939, DOI 10.1007/s10948-013-2144-1. - ISSN 1557-1947
Аннотация: We consider the doping dependence of the normal and superconducting properties of La2Sr2−x CuO2 and YBa2Cu3O7 in the low energy effective model based on the ab initio LDA+GTB calculations. With doping we have found a concentration region with electronic instability of the uniform state. We have shown that two quantum phase transitions (QPT) of the Lifshitz type correspond well to the experimental phase diagram. For superconducting state we have considered both magnetic and phonon mechanisms of pairing.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Aleksandrovsky A. S., Atuchin V. V., Kesler V. G., Zaitsev A. I., Molokeev M. S., Kuzubov A. A., Ignatova N. Y.
Заглавие : Electronic structure of α-SrB4O7: Experiment and theory
Коллективы : Russian-French workshop on Nanosciences and Nanotechnologies, Российская академия наук, Сибирское отделение РАН, Институт неорганической химии им. А.В. Николаева Сибирского отделения РАН, Институт катализа им. Г.К. Борескова Сибирского отделения РАН, Институт физики полупроводников им. А.В. Ржанова Сибирского отделения РАН
Место публикации : The 7th Russian-French workshop on Nanosciences and Nanotechnologies: Program and abstract book/ ed. A. V. Okotrub. - Novosibirsk, 2013. - P.47. - ISBN 978-5-901688-29-8
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Eliseeva N. S., Krasnov P. O., Tomilin F. N., Fedorov A. S., Tolstaya A. V.
Заглавие : Possibility of a 2D SiC monolayer formation on Mg(0001) and MgO(111) substrates
Место публикации : Russ. J. Phys. Chem. A: MAIK Nauka-Interperiodica / Springer, 2013. - Vol. 87, Is. 8. - P.1332-1335. - ISSN 0036-0244, DOI 10.1134/S0036024413080141
Примечания : Cited References: 25
Предметные рубрики: AB-INITIO
THIN-FILMS
NANOTUBES
ENERGY
Ключевые слова (''Своб.индексиров.''): silicon carbide monolayer--density functional theory
Аннотация: The geometrical characteristics of a 2D SiC monolayer on Mg(0001) and MgO(111) plates regarded as potential materials for growing two-dimensional silicon carbide were studied. The most favorable positions of the atoms of 2D SiC on the substrates were determined. In the 2D SiC/Mg(0001) system, unlike in 2D SiC/MgO(111), the deviation of the carbon atom from the silicon carbide monolayer was insignificant (0.08 ). Consequently, magnesium can be used as a substrate for growing two-dimensional silicon carbide. The use of MgO(111) is not recommended because of a significant distortion of the 2D SiC surface.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Nikolaev S., Shneyder E. I., Krinitsyn A.
Заглавие : Normal and superconducting properties of cuprates in multielectron theory
Место публикации : J. Supercond. Nov. Magn. - 2013. - Vol. 26, Is. 9. - P.2831-2835. - ISSN 1557-1939, DOI 10.1007/s10948-013-2263-8
Ключевые слова (''Своб.индексиров.''): cluster perturbation theory--fermi surface reconstruction--strong electron correlations
Аннотация: We consider the doping dependence of the normal and superconducting properties of La2-x Srx CuO4 in the low energy effective model based on the ab initio LDA+GTB calculations. We have found that two quantum phase transitions (QPT) of the Lifshitz type correspond well to the experimental phase diagram. For superconducting state, we have considered both magnetic and phonon mechanisms of pairing. Finally, we compare the true Fermi surface and the spectral intensity map seen in ARPES within a new norm conserving cluster perturbation theory (NC-CPT). В© 2013 Springer Science+Business Media New York.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Orlov Yu.S., Ovchinnikov S. G., Dudnikov V. A., Fedorov A. S., Kuzubov A. A.
Заглавие : Structural properties and high temperature spin and electronic transitions in GdCoO[[d]]3[[/d]]: experiment and theory
Коллективы : Euro-Asian Symposium "Trends in MAGnetism": Nanomagnetism
Место публикации : V Euro-Asian simposium "Trend in MAGnetism": Nanomagnetism: abstracts. - Vladivostok: FEFU, 2013. - С. 200. - ISBN 978-5-7444-3124-2
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zamkova N. G., Zhandun V. S., Zinenko V. I.
Заглавие : First-principles calculations of ferroelectric properties in AA`BB`O6 double perovskites with different types of cation ordering
Место публикации : Phys. status solidi B. - 2013. - Vol. 250, Is. 9. - P.1888-1897. - ISSN 0370-1972, DOI 10.1002/pssb.201349084
Ключевые слова (''Своб.индексиров.''): density functional theory--double perovskites--ferroelectrics--polarization
Аннотация: First-principles calculations of lattice dynamics and polarization properties have been performed for double perovskite ABiBNbO6 (A - alkali metal Na, Rb, and B - trivalent metal Sc, Lu). Three possible types of A- and B-site cation ordering are studied: layer and columnar ordering of A-site cations with rocksalt ordering of B-site cations, and layer ordering of both cations. The ground state of all compounds is polar with a large value of polarization for all types of cation ordering. For some compounds we obtain spontaneous polarization of 0.7-1.0Cm-2 that is twice the BaTiO3 value. For RbBiScNbO6 the lowest-energy state has layer ordering of both A- and B-site cations, which is rare for compounds with double-perovskite structure.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R., Mantica G.
Заглавие : Cyclotron-Bloch dynamics of a quantum particle in a two-dimensional lattice
Место публикации : Physical Review E - Statistical, Nonlinear, and Soft Matter Physics. - 2011. - Vol. 83, Is. 4. - Ст.041123. - ISSN 1539-3755, DOI 10.1103/PhysRevE.83.041123
Ключевые слова (''Своб.индексиров.''): critical value--directed transport--drift velocities--electric and magnetic fields--electric field magnitude--electric field vectors--free space--initial conditions--lattice plane--quantum dynamics--quantum particles--quantum wave packets--two dimensional square lattice--two-dimensional lattices--electric fields--magnetic fields--quantum theory--vector spaces--two dimensional
Аннотация: This paper studies the quantum dynamics of a charged particle in a two-dimensional square lattice, under the influence of electric and magnetic fields, the former being aligned with one of the lattice axes and the latter perpendicular to the lattice plane. While in free space these dynamics consist of uniform motions in the direction orthogonal to the electric field vector, we find that, in a lattice, this directed drift takes place only for specific initial conditions and for electric field magnitudes smaller than a critical value. Otherwise, the quantum wave packet spreads ballistically in both directions orthogonal to the electric field. We quantify this ballistic spreading and identify the subspace of initial conditions ensuring directed transport with the drift velocity. We also describe the effect of disorder in the system. В© 2011 American Physical Society.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Korshunov M. M., Nikolaev S. N., Shneyder E. I.
Заглавие : Quantum phase transitions and superconductivity in single- and two-layer cuprates in the multiband theory of Hubbard fermions
Коллективы : Ettore Majorana Foundation, Centre for Scientific Culture, Rome International Center for Materials Science, International School of Solid State Physics, "Phase separation and Superstripes in High Temperature Superconductors and Related Materials", Int. Conf. (55; 2012 ; July ; 11-17; Erice (Sicily), Italy)
Место публикации : International conferences «Phase separation and Superstripes in High Temperature Superconductors and Related Materials (Superstripes-2012)». - 2012. - P.128
Аннотация: We consider the doping dependence of the normal and superconducting properties of LaSrCuO and YBaCuO in the low energy effective model based on the ab initio LDA+GTB calculations. With doping we have found a concentration region with electronic instability of the uniform state. We have shown that two quantum phase transitions (QPT) of the Lifshitz type correspond well to the experimental phase diagram. For superconducting state we have considered both magnetic and phonon mechanisms of pairing.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Orlov Yu.S., Solovyov L. A., Dudnikov V. A., Fedorov A. S., Kuzubov A. A., Kazak N. V., Voronov V. N., Vereshchagin S. N., Shishkina N. N., Perov N. S., Lamonova K. V., Babkin R.Yu., Pashkevich Yu.G., Anshits A. G., Ovchinnikov S. G.
Заглавие : Structural properties and high-temperature spin and electronic transitions in GdCoO3: Experiment and theory
Место публикации : Phys. Rev. B: American Physical Society, 2013. - Vol. 88, Is. 23. - Ст.235105. - P. - ISSN 1098-0121, DOI 10.1103/PhysRevB.88.235105
Аннотация: We have investigated the x-ray diffraction (XRD) structure, magnetic susceptibility, and heat capacity of GdCoO3 in a wide temperature range. A model of phase separation of the low-spin (LS) and high-spin (HS) states has been proposed based on the analysis of XRD peak shape anomalies in the temperature range 200-800 K. From magnetic measurements we separated the HS Co3+ contribution and fitted it with the temperature-dependent spin gap. We found a smooth LS-HS crossover at T=800 K. The possible contribution of the intermediate spin (IS) state to the thermodynamics is excluded by the calculation IS-LS excitation energy within the modified crystal-field approach. In the two-phase model, with HS/LS probabilities calculated from the found spin gap and the LS and HS volumes calculated by the DFT-GGA method, we were able to reproduce the temperature dependence of the unit-cell volume and thermal expansion. Thus, we conclude that in GdCoO3 the main mechanism of the lattice expansion is not the conventional lattice anharmonicity, but the HS/LS fluctuations. The electronic structure has been calculated by the LDA+GTB method. At zero temperature, we have obtained the charge-transfer insulator with the charge gap Eg=0.5 eV. The thermal population of the HS term results in the in-gap band formation inside the insulator gap and smooth insulator-metal transition at TIMT=780 K. Heat-capacity measurements revealed a smooth maximum near the TIMT. © 2013 American Physical Society.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Karpov S. V., Semina P. N.
Заглавие : On coagulation of polydisperse metal nanocolloids and conditions for applicability of the Muller-Smoluchowski theory
Место публикации : Colloid J.: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 74, Is. 3. - P.295-304. - ISSN 1061-933X, DOI 10.1134/S1061933X12030040
Примечания : Cited References: 15. - Authors are thankful to G. A. Chiganova and A. P. Gavrilyuk for discussions and helpful comments. Studies were carried out with the support of grants: the Presidium of RAS No 29 and No 31, OFN RAS III.9.5, IP SB RAS No 43, IP SB RAS (and SFU) No 101.
Аннотация: The regularities of the coagulation of metal nanocolloids with different degrees of polydispersity are studied by the Brownian dynamics method. The results of the numerical calculations of coagulation kinetics are compared with the conclusions of the Muller-Smoluchowski theory. It is revealed that these data deviate from the predictions of the theory upon a decrease in the viscosity of dispersion medium, an increase in the thickness of layers adsorbed on particles, and the combination of these factors. It is demonstrated that no acceleration of the colloid coagulation with a rise in the degree of polydispersity, which is predicted by the theory, takes place under these conditions.
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12.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Edelman I. S., Ivanova O. S., Ivantsov R. D., Stepanov S., Zaikovskiy V. I.
Заглавие : Heat treatment stimulation of the magnetic nanoparticles formation in borate glasses doped with transition elements
Место публикации : Heat Treat.: Theory, Tech. and Appl.: Chapter. - New York: Nova Science Publishers, 2011. - P.225-239. - ISBN 978-161728348-2
Аннотация: Evolution of the magnetic nanoparticles characteristics in glasses of the system 22.5 Al2O3 - 22.5 K2O - 55 B2O3 co-doped with Fe2O3 and MnO simultaneous is studied at different stages of the post-synthesis heat treatment with transmission electron microscopy (TEM) images, selected area electron diffraction (SAED), energy dispersive X-ray analysis (EDAX), and magneto-optical Faraday rotation (FR). Heat treatment of the glasses results in substantial changes of their structure and properties: ferrite nanoparticles of different size, composition, and structure arise in glass matrices. For several series of glasses with the same composition and molar concentration of the paramagnetic additions, the heat treatment regimes (temperature and duration) have been shown to be the main factors controlling the particle size and the order in the crystallite arrangements. Ensembles of particles in theirs turn determine magnetic and magneto-optical properties of glass as a whole. A correlation between the characteristics of nanoparticles and the heat treatment regimes is discussed qualitatively.
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13.

Вид документа : Статья из журнала
Шифр издания : Physics, Applied/C94
Автор(ы) : Korshunov M. M., Ovchinnikov S. G., Shneyder E. I., Gavrichkov V. A., Orlov Yu.S., Nekrasov I. A., Pchelkina Z. V.
Заглавие : Cuprates, manganites and cobaltites: Multielectron approach to the band structure
Место публикации : Mod. Phys. Lett. B: WORLD SCIENTIFIC PUBL CO PTE LTD, 2012. - Vol. 26, Is. 24. - Ст.1230016. - ISSN 0217-9849, DOI 10.1142/S0217984912300165
Примечания : Cited References: 93. - We are thankful to O. K. Andersen, V. I. Anisimov, A. F. Barabanov, K. I. Kikoin, N. M. Plakida, S. Sakai, A.-M.S. Tremblay, V. V. Val'kov, and R. O. Zaitsev for useful discussions. This work was supported by the Presisium of RAS program Quantum physics of condensed matter N 20.7, Grant "Leading scientific schools of Russia" (NSh 1044-2012.2), RFBR (Grant No. 09-02-00127), Integration Grant of SBRAS-UrBRAS N 44, Grant of President of Russia MK-1683.2010.2, FCP Scientific and Research-and-Educational Personnel of Innovative Russia for 2009-2013 (GK 16.740.12.0731 and GK 16.740.11.0740), and Siberian Federal University (Theme N F-11). M.M.K. and E.I.S. acknowledges support from The Dynasty Foundation and ICFPM.
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
MEAN-FIELD THEORY
DENSITY-FUNCTIONAL FORMALISM
CORRELATED ELECTRON-SYSTEMS
TRANSITION-METAL COMPOUNDS
SPIN-STATE TRANSITION
T-J MODEL
MAGNETIC-PROPERTIES
COPPER OXIDES
LaCoO3
Ключевые слова (''Своб.индексиров.''): lda plus gtb method--strongly-correlated systems--band structure
Аннотация: High-T-c superconductors with CuO2 layers, manganites La1-xSrxMnO3 and cobaltites LaCoO3 present several mysteries in their physical properties. Most of them are believed to come from the strongly-correlated nature of these materials. From the theoretical viewpoint, there are many hidden rocks in making the consistent description of the band structure and low-energy physics starting from the Fermi-liquid approach. Here, we discuss the alternative method - multielectron approach to the electronic structure calculations for the Mott insulators - called LDA + GTB (local density approximation + generalized tight-binding) method. Its origin is a straightforward generalization of the Hubbard perturbation theory in the atomic limit and the multiband p - d Hamiltonian with the parameters calculated within LDA. We briefly discuss the method and focus on its applications to cuprates, manganites and cobaltites.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Martynov S. N.
Заглавие : Incommensurate structures in a two-subsystem partially frustrated ferrimagnet
Место публикации : JETP Letters. - 2012. - Vol. 95, Is. 4. - P.188-192. - ISSN 0021-3640, DOI 10.1134/S0021364012040066
Примечания : Cited References: 23. - This work was supported by the Russian Foundation for Basic Research (project no. 10-02-00765).
Предметные рубрики: CLASSICAL-THEORY
MAGNETIC-FIELD
ANTIFERROMAGNET
CUB2O4
STATE
Аннотация: A new incommensurate magnetic structure with a locally triangular orientation of spins has been proposed for a two-subsystem magnet with frustrated intersystem exchange and competition between exchanges in one of the subsystems. When the temperature is lowered, this structure appears from the antiferromagnetic state after a first-order phase transition. It transfers to the Yafet-Kittel triangular structure when the threshold conditions for the exchange interactions are fulfilled. An increase in the length of the frustrated exchange bonds leads to the appearance of an incommensurate phase with the local antiferromagnetic orientation of the sublattices in each subsystem between the commensurate antiferromagnetic and Yafet-Kittel phases.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Nikolaev S. V., Ovchinnikov S. G.
Заглавие : Effect of hole doping on the electronic structure and the Fermi surface in the Hubbard model within norm-conserving cluster pertubation theory
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 114, Is. 1. - P.118-131. - ISSN 1063-7761, DOI 10.1134/S1063776111150143
Примечания : Cited References: 51. - This study was supported financially by the Russian Foundation for Basic Research (project nos. 10-02-90725-mob_st and 09-02-00127), Program 18.7 of the Presidium of the Russian Academy of Sciences, the Federal Target Program "Personnel" (state contract no. P891), and the integrated project no. 40 of the Siberian Branch of the Russian Academy of Sciences.
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTORS
NARROW ENERGY-BANDS
CORRELATED ELECTRONS
PSEUDOGAP
EVOLUTION
La2-XSRXCuO4
INSULATOR
Аннотация: The concentration dependences of the band structure, spectral weight, density of states, and Fermi surface in the paramagnetic state are studied in the Hubbard model within cluster pertubation theory with 2 x 2 clusters. Representation of the Hubbard X operators makes it possible to control conservation of the spectral weight in constructing cluster perturbation theory. The calculated value of the ground-state energy is in good agreement with the results obtained using nonperturbative methods such as the quantum Monte Carlo method, exact diagonalization of a 4 x 4 cluster, and the variational Monte Carlo method. It is shown that in the case of hole doping, the states in the band gap (in-gap states) lie near the top of the lower Hubbard band for large values of U and near the bottom of the upper band for small U. The concentration dependence of the Fermi surface strongly depends on hopping to second (t') and third (t '') neighbors. For parameter values typical of HTSC cuprates, the existence of three concentration regions with different Fermi surfaces is demonstrated. It is shown that broadening of the spectral electron density with an energy resolution typical of contemporary ARPES leads to a pattern of arcs with a length depending on the concentration. Only an order-of-magnitude decrease in the linewidth makes it possible to obtain the true Fermi surface from the spectral density. The kinks associated with strong electron correlations are detected in the dispersion relation below the Fermi level.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sadreev A. F.
Заглавие : Feshbach projection formalism for transmission through a time-periodic potential
Место публикации : Phys. Rev. E: American Physical Society, 2012. - Vol. 86, Is. 5. - Ст.56211. - ISSN 1539-3755, DOI 10.1103/PhysRevE.86.056211
Примечания : Cited References: 33
Предметные рубрики: NUCLEAR REACTIONS
UNIFIED THEORY
QUANTUM
FIELD
SCATTERING
SYSTEM
STATES
Аннотация: The Feshbach projection formalism is applied to consider quantum transmission through a tight-binding wire subject to a time-periodic potential. The wire is coupled with two leads via the coupling constant v(C). The periodicity of the potential implies an additional temporal dimension that reduces the problem to stationary transmission through an effectively two-dimensional lattice system. The non-Hermitian effective Hamiltonian is formulated. Thist allows us to trace the redistribution of resonance positions and resonance widths with the growth of v(C) from the weak-coupling to the strong-coupling regime.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krinitsyn A., Nikolaev S., Ovchinnikov S. G.
Заглавие : Cluster size and shape effect on the electronic structure of the Hubbard model within the norm-conserving cluster perturbation theory
Коллективы : Siberian Federal University [F-11]; Presidium of RAS Program [20.7]; [NSh-1044.2012.2]; [MK-1168.2012.2]
Место публикации : J. Supercond. Nov. Magn.: Springer, 2014. - Vol. 27, Is. 4. - P.955-963. - ISSN 1557-1939, DOI 10.1007/s10948-013-2418-7. - ISSN 1557-1947
Примечания : Cited References: 59. - This work was supported by Grants NSh-1044.2012.2 and MK-1168.2012.2, Siberian Federal University: Grant F-11, and the Presidium of RAS Program 20.7.
Предметные рубрики: NARROW ENERGY-BANDS
CUPRATE SUPERCONDUCTORS
PHOTOEMISSION SPECTRA
PSEUDOGAP
ANTIFERROMAGNET
EXCITATIONS
EVOLUTION
SYSTEMS
PHASE
STATE
Ключевые слова (''Своб.индексиров.''): cluster perturbation theory--hubbard model--strong correlations--density of states--fermi surface
Аннотация: Within a new norm-conserving approach to the cluster perturbation theory (CPT) for the 2d Hubbard model we study the effect of the cluster size and shape on the electronic structure. We have compared two type of clusters, 4-cluster (2x2) and 5-cluster (cruciform of 5 atoms). With 4-cluster we can treat exactly the first and second neighbours correlations, C (1) and C (2). With 5-cluster the third neighbour correlations C (3) are also treated exactly. The band structure in the CPT with 4- and 5-clusters differs remarkably. The quasiparticle spectral weight map for 5-clusters is very similar to the Quantum Monte Carlo (QMC) and the variational CPT data. With increasing doping, small hole Fermi surface transforms into conventional Fermi-liquid type large Fermi surface through Lifshitz quantum phase transitions.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Tikhonova L. V., Fedorov A. S.
Заглавие : Ab initio investigation of a new boron nitride allotrope
Коллективы : Russian Foundation for Basic Research [12-02-00640]
Место публикации : Phys. Status Solidi B. - 2014. - Vol. 251, Is. 6. - P.1282-1285. - ISSN 0370-1972, DOI 10.1002/pssb.201350389. - ISSN 1521-3951
Примечания : Cited References: 31. - We acknowledge support of the Russian Foundation for Basic Research through Grant No. 12-02-00640. Also, we thank the Institute of Computer Modeling (Siberian Division, Russian Academy of Sciences, Krasnoyarsk), the Joint Supercomputer Center of the Russian Academy of Sciences (Moscow), the computer cluster "Chebyshev" of the Moscow State University (Moscow), and the supercomputer of the Institute of Space and Information Technologies of the Siberian Federal University for providing an opportunity to use their computers for performing all calculations.
Предметные рубрики: AUGMENTED-WAVE METHOD
MOLECULAR-DYNAMICS
TRANSITION
METALS
Ключевые слова (''Своб.индексиров.''): boron nitride--computational materials science--density functional theory--elastic properties--superhard materials
Аннотация: A new allotropic superhard and superdense structure of sp3-bonded boron nitride (hP3-BN) is proposed. Geometric electronic, elastic, and optical properties of the structure are investigated by density functional theory generalized gradient approximation (DFT-GGA) calculations. It is shown that the structure is an insulator with a band gap of 5.06 eV; is density is 5.03% higher than that of cubic boron nitride (c-BN) and its bulk modulus is 2.25% higher than that of c BN. The calculated hP3-BN refractive index in the range 200-800 nm is significantly higher than the indexes of diamond and all known carbon allotropes, expect for the analogous carbon h-P3 structure, and it has a large optical dispersion. In the range above 800 nm the refractive index changes from 2.60 to 2.35. (C) WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Popov M. A., Zavislyak I. V., Movchan N. N., Gudim, I. A., Srinivasan G.
Заглавие : Mode splitting in 37-42 GHz barium hexaferrite resonator: Theory and device applications
Место публикации : IEEE Trans. Magn.: IEEE-Institute Electrical and Electronics Engineers, 2014. - Vol. 50, Is. 6. - Ст.4004507. - ISSN 0018-9464, DOI 10.1109/TMAG.2014.2298498. - ISSN 1941-0069
Примечания : Cited References: 34
Предметные рубрики: MILLIMETER-WAVE APPLICATIONS
GUIDE JUNCTION CIRCULATORS
FERRITE
MICROWAVE
PROPAGATION
CYLINDERS
Ключевые слова (''Своб.индексиров.''): dielectric resonance--ferromagnetic resonance (fmr)--hexagonal ferrite--isolator--phase shifter
Аннотация: Dielectric resonances in the 37-42 GHz frequency band in the single crystal barium hexaferrite that occur well below the ferromagnetic resonance (FMR) have been investigated. Sample dimensions have been chosen so that the mode frequency is lower than the spin-wave excitation (in this case, the natural domain resonance) frequency. Such dielectric mode frequencies, being a function of both permittivity and permeability, are magnetic field H tunable. Here, we report on below-FMR magnetodielectric resonance (MDR) axially magnetized barium hexaferrites and their H-tuning characteristics. Our studies reveal H-tuning by up to 2.5 GHz and the tuning is the largest when the ferrite is in a magnetically unsaturated state. A theory for the MDR is presented and a fairly good agreement between experimental data and theory has been obtained. Tunable millimeter wave phase shifters and isolators utilizing the below-FMR dielectric resonances have been demonstrated.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Burkov S. I., Sorokin B. P., Glushkov D. A., Aleksandrov K. S.
Заглавие : Theory and computer simulation of the reflection and refraction of bulk acoustic waves in piezoelectrics under the action of an external electric field
Место публикации : Crystallogr. Rep. - 2005. - Vol. 50, Is. 6. - P.986-993. - ISSN 1063-7745, DOI 10.1134/1.2132408
Примечания : Cited References: 11
Аннотация: The basic equations describing the conditions for reflection and refraction of bulk acoustic wave at the interface between acentric crystals subjected to the action of a uniform external electric field are reported. Numerical analysis of the effect of this field on the reflection and refraction anisotropy of bulk acoustic waves at the crystal/vacuum and piezoelectrie/elastic-isotropic-medium interfaces is performed. (C) 2005 Pleiades Publishing, Inc.
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