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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Кузьмин, Валерий Ипполитович, Николаев, Сергей Викторович
Заглавие : Исследование аномалий электронной дисперсии в модели Хаббарда, t-J- и t-J*-модели в рамках кластерной теории возмущений в представлении Х-операторов
Коллективы : Сибирский молодежный семинар по высокотемпературной сверхпроводимости и физике наноструктур – ОКНО 2014 (X; 13 - 14 ноября 2014 г.; Новосибирск)
Место публикации : Вестник НГУ. Физика. - 2015. - Т. 10, Вып. 1. - С. 50-56. - ISSN 1818-7994
Примечания : Библиогр.: 23. - Работа выполнена при финансовой поддержке Российского научного фонда (проект № 14-12-00061).
Ключевые слова (''Своб.индексиров.''): высокотемпературная сверхпроводимость--электронная структура купратов--высокоэнергетические кинки--кластерные теории--модель хаббарда--t-j-модель--high-temperature superconductivityory--electronic structure of cuprates--high-energy kinks--cluster perturbation theory--hubbard model--t-j-model
Аннотация: В рамках кластерной теории возмущений в представлении Х-операторов Хаббарда рассчитана энергетическая структура электронов в модели Хаббарда, t-J- и t-J *-модели с учетом уширения спектральных линий, соответствующего экспериментам по фотоэмиссионной спектроскопии с угловым разрешением. При энергиях порядка интеграла перескока t в полученных спектрах наблюдаются аномалии, схожие с высокоэнергетическими кинками, наблюдаемыми в экспериментах по фотоэмиссионной спектроскопии с угловым разрешением. Исследовано поведение высокоэнергетических аномалий электронной дисперсии при изменениях величины допирования и параметра кулоновского отталкивания. Проанализировано влияние трехцентровых коррелированных перескоков на результаты расчета.The electronic structure with the spectral line broadening corresponding to the angle-resolved photoemission spectroscopy resolution has been calculated for the Hubbard model, t-J and t-J * models within the norm-conserving cluster perturbation theory. The electronic dispersion anomalies similar to the high-energy kinks observed in the angle-resolved photoemission spectroscopy experiments are obtained at the energy scale of order of the hopping integral t. The doping dependence of the high-energy anomalies for different Coulomb repulsion values is discussed. The influence of the three-site correlated hopping on the results is analyzed.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : GORYACHEV E. G.
Заглавие : VARIATIONAL APPROACH TO THE 3-PARTICLE PROBLEM IN THE HUBBARD-MODEL - THE EXACT RESULT
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz.: MEZHDUNARODNAYA KNIGA, 1992. - Vol. 102, Is. 4. - P1280-1285. - ISSN 0044-4510
Примечания : Cited References: 7
Аннотация: A well-defined procedure for the linearization of the equations of motions, which is based on the stationary principle, is proposed. In the special case of a flopped spin in the saturated ferromagnetic state (three-particle problem) the single-particle Green function is found. It is proved that regardless whether the initial (unperturbed) state is a strong coupling band (Bloch representation) or two-level atom system (Hubbard representation) the results for the single-particle Green function coincide for arbitrary values of the hamiltonian constants and electron concentration b up. In the non-trivial limit case U = infinity such a Green function coincides with the exact result of Igarashi - Ruckenstein - Schmitt - Rink [2,3] based on solving the Faddeev equations.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Efremov D. V., Marienko M. S., Val'kov V. V.
Заглавие : Triplet p-Wave Superconductivity in the Low-Density Extended Hubbard Model with Coulomb Repulsion
Разночтения заглавия :авие SCOPUS: Triplet p-wave superconductivity in the low-density extended hubbard model with Coulomb repulsion
Место публикации : JETP Letters. - 2011. - Vol. 93, Is. 12. - P.725-730. - ISSN 0021-3640, DOI 10.1134/S0021364011120083
Примечания : Cited References: 42. - We acknowledge useful with A. V. Chubukov, A.S. Alexandrov, I.A. Fomin, K.I. Kugel, and V. V. Kabanov for stimulating discussions. This work was supported by the Russian Foundation for Basic Research (project nos. 11-02-00708 and 11-02-00741). M.S.M acknowledges the support of the US Department of Energy (award no. DE-FG02-08ER64623, Hofstra University Center for Condensed Matter).
Предметные рубрики: T-J MODEL
FERMI GAS
SUPERFLUID TRANSITION
PHASE-SEPARATION
SYSTEMS
TEMPERATURES
BEHAVIOR
LIQUID
POINT
STATE
Аннотация: We analyze superconducting instabilities in 3D and 2D extended Hubbard model with Coulomb repulsion between electrons on neighboring sites in the limit of low electron density (n(el) - 0) on simple cubic (square) lattice. We show that in a realistic strong-coupling case U V W (U and V are the onsite and the intersite Coulomb repulsions, respectively, and W the bandwidth) the main SC instability corresponds to the p-wave pairing and in the leading order is correctly described by the equations obtained earlier in the absence of the intersite Coulomb interaction V = 0.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kolovsky A. R.
Заглавие : Treating many-body quantum systems by means of classical mechanics
Коллективы : International Conference on Nonlinear Dynamics of Electronic Systems
Место публикации : Springer Proceedings in Physics: Springer, 2017. - Vol. 191. - P.37-48. - ISSN 09308989 (ISSN); 9783319478081 (ISBN), DOI 10.1007/978-3-319-47810-4_4
Примечания : Cited References: 16
Ключевые слова (''Своб.индексиров.''): dynamical systems--dynamics--hubbard model--optical lattices--quantum optics--classical mechanics--energy spectra--identical particles--many-body quantum systems--paradigmatic models--quantum many-body systems--quantum physics--semiclassical approaches--quantum theory
Аннотация: Many-body physics of identical particles is commonly believed to be a sovereign territory of Quantum Mechanics. The aim of this contribution is to show that it is actually not the case and one gets useful insights into a quantum many-body system by using the theory of classical dynamical systems. In the contribution we focus on one paradigmatic model of many-body quantum physics - the Bose– Hubbard model which, in particular, describes interacting ultracold Bose atoms in an optical lattice. We show how one can find/deduce the energy spectrum of the Bose–Hubbard model by using a kind of the semiclassical approach. © Springer International Publishing AG 2017.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Makarov I. A., Shneyder E. I., Kozlov P. A., Ovchinnikov S. G.
Заглавие : Transition between large and small polaron states in the electronic structure of HTSC cuprates
Коллективы : RFBR [13-02-01395 a, 14-02-31677 mol_a]
Место публикации : J. Supercond. Nov. Magn.: Springer, 2016. - Vol. 29, Is. 4. - P.1063-1068. - ISSN 1557-1939, DOI 10.1007/s10948-016-3375-8. - ISSN 1557-1947(eISSN)
Примечания : Cited References:10. - This work was funded by RFBR according to the research projects No. 13-02-01395 a and No. 14-02-31677 mol_a.
Предметные рубрики: SUPERCONDUCTIVITY
Ключевые слова (''Своб.индексиров.''): cuprates--strong electron correlations--electron-phonon interaction--polaron--franck-condon process--hubbard fermions--band structure
Аннотация: The effect of strong electron correlations (SEC) and strong electron-phonon interaction (EPI) on the electronic structure of cuprates is studied within the polaronic version of the generalized tight binding method. Both diagonal and off-diagonal EPI in terms of ionic coordinates are considered.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Val'kova T. A., Dzebisashvili D. M., Ovchinnikov S. G.
Заглавие : Three-center interactions and magnetic mechanism of superconductivity with dx2-y2-symmetry in the t-J*-model
Коллективы : International Conference on Modern Problems in Superconductivity
Место публикации : Mod. Phys. Lett. B/ International Conference on Modern Problems in Superconductivity (3 ; 2002 ; Sept. ; 9-14 ; Yalta, Ukrain). - 2003. - Vol. 17, Is. 10-12. - P.441-449. - ISSN 0217-9849, DOI 10.1142/S0217984903005469
Примечания : Cited References: 12
Предметные рубрики: BAND HUBBARD-MODEL
Аннотация: The effect of three-center interactions on the formation of a superconducting phase with d(x2-y2)-symmetry is considered using the diagram technique for Hubbard operators and irreducible Green's functions. It is shown that these interactions lead to a decrease in T-c by a factor of several tens.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min E. V., Baklanov I. O.
Заглавие : The singlet state in the Hubbard model with U=infinity
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 1998. - Vol. 87, Is. 6. - P1159-1166. - ISSN 1063-7761, DOI 10.1134/1.558607
Примечания : Cited References: 16
Предметные рубрики: HOLES
Аннотация: We discuss, in connection with the problem of the ground state in the Hubbard model with U = infinity, the normal (nonmagnetic) N-state of a system over the entire range of electron concentrations n less than or equal to 1. It is found that in a one-particle approximation, e. g., in the generalized Hartree-Fock approximation, the energy epsilon(0)(n) of the N-state is lower than the energy epsilon(FM)(n) of a saturated ferromagnetic state for all values of n. Using the random phase approximation we calculate the dynamical magnetic susceptibility and show that the N-state is stable for all values of n. A formally exact representation is derived for the mass operator of the one-particle electron Green's function, and its expression in the self-consistent Born approximation is obtained. We discuss the first Born approximation and show that when correlations are taken into account, the attenuation vanishes on the Fermi surface and the electron distribution function at T = 0 acquires a Migdal discontinuity, whose magnitude depends on n. The energy of the N-state in this approximation is still lower than epsilon(FM)(n) for n 1.We show that the spin correlation functions are isotropic, which is a characteristic feature of the singlet states of the system. We calculate the spin correlation function for the nearest neighbors in the zeroth approximation as a function of n. Finally, we conclude that the singlet state of the system in the thermodynamic limit is the ground state. (C) 1998 American Institute of Physics. [S1063-7761(98)01712-0].
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kovaleva E. A., Melchakova I., Mikhaleva N. S., Tomilin F. N., Ovchinnikov S. G., Baek W., Pomogaev V. A., Avramov P. V., Kuzubov A. A.
Заглавие : The role of strong electron correlations in determination of band structure and charge distribution of transition metal dihalide monolayers
Место публикации : J. Phys. Chem. Solids. - 2019. - Vol. 134. - P.324-332. - ISSN 00223697 (ISSN), DOI 10.1016/j.jpcs.2019.05.036
Примечания : Cited References: 44. - This work was supported by the government contract of the Ministry of Education and Science of the Russian Federation, Russia to Siberian Federal University (Grant No. 16.1455.2017/PCh ) and Russian Foundation for Basic Research (RFBR), Russia (Grant No. 16-32-60003 mol_a_dk), Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project: “Quantum chemical modeling of Bychkov-Rashba interfaces based on transition metal compounds and nanoscaled organic fragments” (Project No. 18-43-243011). The authors would like to thank Joint Supercomputer Center of RAS , Moscow; Center of Equipment for Joint Use of Siberian Federal University , Krasnoyarsk; and Information Technology Center, Novosibirsk State University for providing the access to their supercomputers. N.S.M. acknowledges the financial support of the RFBR , through the research project No. 16-32-60003 mol_a_dk. E.A. Kovaleva is grateful to the Foundation for Assistance to Small Innovative Enterprises (FASIE), Russia (Project no. 0033639 ). W.B. and P.A. gratefully acknowledge the financial support of National Research Foundation of Republic of Korea under the Grant No. NRF-2017R1A2B4004440.
Аннотация: Electronic structure and magnetic properties of the family of first-row transition metal dihalides (TMHal2, TM = V, Cr, Mn, Fe, Co, Ni; H = Br, I) monolayers were studied by means of density functional theory. Strong electron correlations were taken into account by implementing Hubbard U correction in a simplified scheme proposed by Dudarev et al. (Ueff). Ueff correction essentially affects electronic structure of TMHal2 widening the band gap and witnessing their highly spin-polarized nature. Two different ligand orientations namely, H and T configurations of monolayers were considered. Unlike others, FeHal2 monolayers tend to form H structure when Ueff correction is included. © 2019 Elsevier Ltd
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Ovchinnikov S. G., Yakimov L. E.
Заглавие : The role of orbital ordering in the formation of electron structure in undoped LaMnO3 manganites in the regime of strong electron correlations
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 102, Is. 6. - P972-985. - ISSN 1063-7761, DOI 10.1134/S1063776106060112
Примечания : Cited References: 25
Предметные рубрики: COLOSSAL MAGNETORESISTIVE OXIDES
DOUBLE EXCHANGE
BAND
MODEL
Ключевые слова (''Своб.индексиров.''): computational methods--correlation methods--doping (additives)--electrons--ferromagnetic materials--lanthanum compounds--paramagnetic materials--intraatomic electron correlations--mott hubbard correlation gap--orbital ordering--paramagnetic phases--electronic structure
Аннотация: The electron structure of undoped LaMnO3 and slightly doped La1-xSrxMnO3 manganites has been calculated within the framework of a generalized tight binding method with explicit allowance for strong intra-atomic electron correlations. According to the results of these calculations, the ground state in orbitally disordered undoped LaMnO3 ferromagnets would be metallic despite the Mott-Hubbard correlation gap in the spectrum of quasiparticles. Owing to the orbital ordering, the insulating state is stabilized in both antiferromagnetic and paramagnetic phases. In-gap states of a polaron nature with a spectral weight proportional to the dopant concentration have been found near the top of the valence band in La1-xSrxMnO3. As the doping level increases, a metal state appears in the ferromagnetic phase, which has a metallic character for one spin subband and an insulating character for the other subband (representing the so-called half-metallic state).
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Golovnya A. A., Dzebisashvili D. M.
Заглавие : The role of anomalous strength operator in the high-T (c) superconductivity theory
Разночтения заглавия :авие SCOPUS: The role of anomalous strength operator in the high- Tc superconductivity theory
Место публикации : Physica B: ELSEVIER SCIENCE BV, 2006. - Vol. 378-80: International Conference on Strongly Correlated Electron Systems (SECES 05) (JUL 26-30, 2005, Vienna, AUSTRIA). - P465-466. - ISSN 0921-4526, DOI 10.1016/j.physb.2006.01.202
Примечания : Cited References: 3
Ключевые слова (''Своб.индексиров.''): superconductivity--t-j-model--superconductivity--t- j-model--approximation theory--frequencies--mathematical operators--numerical methods--superconducting transition temperature--superconductivity--hubbard operator--matsubara frequency--t- j-model--high temperature superconductors
Аннотация: The diagram series structure for Matsubara Green's functions in the Hubbard operators representation have been analyzed for the superconducting (SC) phase in the t-J-model. It has been found that the Hubbard operator diagram technique besides anomalous self-energy operator includes also anomalous strength operator (ASO). With account for ASO Gor'kov equations have been written. ASO are shown to be very essential when anomalous averages are calculated. The anomalous self-energy operator and ASO were derived in one-loop approximation. It has turned out that strength operator components depend oil Matsubara frequency. As a result the SC phase is described by infinite set of integral equations. When deriving the equation for transition temperature in SC phase with s- and d-order parameter symmetry this system has been solved exactly. On the basis of numerical calculations it has been found that the account for strength operator components has fully suppressed SC phase with s-order parameter symmetry in the t-J-model. (c) 2006 Elsevier B.V. All rights reserved.
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