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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rotter I., Sadreev A. F.
Заглавие : Zeros in single-channel transmission through double quantum dots
Место публикации : Phys. Rev. E: AMERICAN PHYSICAL SOC, 2005. - Vol. 71, Is. 4. - Ст.46204. - ISSN 1063-651X, DOI 10.1103/PhysRevE.71.046204
Примечания : Cited References: 28
Предметные рубрики: PHASE EVOLUTION
RESONANCE
TRANSPORT
SYSTEMS
Ключевые слова (''Своб.индексиров.''): fano interference--fano resonances--overlapping resonances--transmission amplitude--channel capacity--eigenvalues and eigenfunctions--function evaluation--hamiltonians--mathematical models--mathematical operators--matrix algebra--resonance--signal interference--semiconductor quantum dots
Аннотация: By using a simple model we consider single-channel transmission through a double quantum dot that consists of two single dots coupled by a wire of finite length L. Each of the two single dots is characterized by a few energy levels only, and the wire is assumed to have only one level whose energy depends on the length L. The transmission is described by using S matrix theory and the effective non-Hermitian Hamilton operator H-eff of the system. The decay widths of the eigenstates of H-eff depend strongly on energy. The model explains the origin of the transmission zeros of the double dot that is considered by us. Mostly, they are caused by (destructive) interferences between neighboring levels and are of first order. When, however, both single dots are identical and their transmission zeros are of first order, those of the double dot are of second order. First-order transmission zeros cause phase jumps of the transmission amplitude by pi, while there are no phase jumps related to second-order transmission zeros. In this latter case, a phase jump occurs due to the fact that the width of one of the states vanishes when crossing the energy of the transmission zero. The parameter dependence of the widths of the resonance states is determined by the spectral properties of the two single dots.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aronov I. E., Berman G. P., Campbell D. K., Dudiy S. V.
Заглавие : Wigner function description of ac transport through a two-dimensional quantum point contact
Разночтения заглавия :авие SCOPUS: Wigner function description of a.c. transport through a two-dimensional quantum point contact
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 1997. - Vol. 9, Is. 24. - P.5089-5103. - ISSN 0953-8984, DOI 10.1088/0953-8984/9/24/009
Примечания : Cited References: 45
Предметные рубрики: QUANTIZED CONDUCTANCE
BALLISTIC-RESISTANCE
CONSTRICTION
CAPACITANCE
ADMITTANCE
ELECTRONS
SYSTEMS
FIELD
PUMP
Аннотация: We have calculated the admittance of a two-dimensional quantum point contact (QPC) using a novel variant of the Wigner distribution function (WDF) formalism. In the semiclassical approximation, a Boltzmann-like equation is derived for the partial WDF describing both propagating and non-propagating electron modes in an effective potential generated by the adiabatic QPC. We show that this quantum kinetic approach leads to the well known stepwise behaviour of the real part of the admittance (the conductance), and of the imaginary part of the admittance (the emittance), in agreement with the latest results derived by Christen and Buttiker, which is determined by the number of propagating electron modes. It is shown that the emittance is sensitive to the geometry of the QPC, and can be controlled by the gate voltage. We have established that the emittance has contributions corresponding to both quantum inductance and quantum capacitance. Stepwise oscillations in the quantum inductance are determined by the harmonic mean of the velocities for the propagating modes, whereas the quantum capacitance is a significant mesoscopic manifestation of the nonpropagating (reflecting) modes.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Maradudin A. A., Poszdnyakov A. V.
Заглавие : Waves in a superlattice with anisotropic inhomogeneities
Место публикации : JETP Letters. - 2003. - Vol. 78, Is. 9. - P.592-596. - ISSN 0021-3640, DOI 10.1134/1.1641491
Примечания : Cited References: 28
Предметные рубрики: PERIODIC MULTILAYERS
SPIN-WAVES
SPECTRUM
LOCALIZATION
SYSTEMS
MEDIA
DISORDER
AVERAGE
Аннотация: Dependences of the dispersion laws and damping of waves in an initially sinusoidal superlattice on inhomogeneities with anisotropic correlation properties are studied for the first time. The period of the superlattice is modulated by the random function described by the anisotropic correlation function K-phi(r) that has different correlation radii, k(parallel toparallel to)(-1) and k(perpendicular to)(-1), along the axis of the superlattice z and in the plane xy, respectively. The anisotropy of the correlation is characterized by the parameter lambda = 1 - k(perpendicular to)/k(parallel toparallel to) that can change from lambda = 0 to lambda = 1 when the correlation wave number k(perpendicular to) changes from k(perpendicular to) = k(parallel toparallel to) (isotropic 3D inhomogeneities) to k(perpendicular to) = 0 (1D inhomogeneities). The correlation function of the superlattice K(r) is developed. Its decreasing part goes to the asymptote L that divides the correlation volume into two parts, characterized by finite and infinite correlation radii. The dependences of the width of the gap in the spectrum at the boundary of the Brillouin zone Deltanu and the damping of waves xi on the value of lambda are studied. It is shown that decreasing L leads to the decrease of Deltanu, and increase of xi, with the increase of lambda. (C) 2003 MAIK "Nauka / Interperiodica".
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Tanner G., Chappell D. J., Maksimov D. N.
Заглавие : Wave Intensity Distributions in Complex Structures
Коллективы : Workshop on Quantum Chaos and Localisation Phenomena
Место публикации : Acta Phys. Pol. A. - 2011. - Vol. 120, Is. 6A. - P.A172-A177. - ISSN 0587-4246
Примечания : Cited References: 19
Предметные рубрики: STATISTICAL ENERGY ANALYSIS
HIGH-FREQUENCIES
SYSTEMS
VIBRATIONS
Аннотация: The vibro-acoustic response of mechanical structures can in general be well approximated in terms of linear wave equations. Standard numerical solution methods comprise the finite or boundary element method in the low frequency regime and statistical energy analysis in the high-frequency limit. Major computational challenges are posed by the so-called mid-frequency problem - that is, composite structures where the local wavelength may vary by orders of magnitude across the components. Recently, a new approach towards determining the distribution of mechanical and acoustic wave energy in complex built-up structures improving on standard statistical energy analysis has been proposed. The technique interpolates between statistical energy analysis and ray tracing containing both these methods as limiting cases. The method has its origin in studying solutions of wave equation with an underlying chaotic ray-dynamics - often referred to as wave chaos. Within the new theory dynamical energy analysis - statistical energy analysis is identified as a low resolution ray tracing algorithm and typical statistical energy analysis assumptions can be quantified in terms of the properties of the ray dynamics. We have furthermore developed a hybrid statistical energy analysis/finite element method based on random wave model assumptions for the short-wavelength components. This makes it possible to tackle mid-frequency problems under certain constraints on the geometry of the structure. Dynamical energy analysis and statistical energy analysis/finite element method calculations for a range of multi-component model systems will be presented. The results are compared with both statistical energy analysis results and finite element method as well as boundary element method calculations. Dynamical energy analysis emerges as a numerically efficient method for calculating mean wave intensities with a high degree of spatial resolution and capturing long range correlations in the ray dynamics.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kliava J., Malakhovskii A. V., Edelman I. S., Potseluyko A. M., Petrakovskaja E. A., Melnikova S.V., Zarubina T. V., Petrovskii G., Bruckental Y., Yeshurun Y.
Заглавие : Unusual magnetic transitions and nature of magnetic resonance spectra in oxide glasses containing gadolinium
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2005. - Vol. 71, Is. 10. - Ст.104406. - ISSN 1098-0121, DOI 10.1103/PhysRevB.71.104406
Примечания : Cited References: 40
Предметные рубрики: ELECTRON-PARAMAGNETIC-RESONANCE
BORATE GLASSES
IONS
BEHAVIOR
GD3+
SPECTROSCOPY
SYSTEMS
GD-3+
FIELD
SHAPE
Ключевые слова (''Своб.индексиров.''): gadolinium--glass--lanthanide--oxide--anisotropy--article--chemical structure--concentration response--electron spin resonance--energy--magnetism--molecular physics--nanoparticle--phase transition--refraction index--temperature sensitivity
Аннотация: Magnetic susceptibility, electron paramagnetic resonance (EPR), and optical properties have been studied in a glass system {20La(2)O(3)-22Al(2)O(3)-23B(2)O(3)-35(SiO2+GeO2)} with a part of La2O3 substituted by Gd2O3 in different concentrations. Positive Weiss constants have been found in the more heavily doped glasses and ascribed to clustering of Gd3+ ions. Two magnetic phase transitions at 55 and 12 K were detected and ascribed, respectively, to ferromagnetic and antiferromagnetic clusters containing Gd ions. The overall shape of the EPR spectra shows the presence of clustering at the higher Gd contents. At low temperatures the cluster-related resonance signal is altered in shape, indicating an onset of magnetic anisotropy field. This signal is convincingly fitted to superparamagnetic resonance arising from ferromagnetic nanoparticles. The clustering, depending on the Gd concentration, correlates with a significant shift to lower energies of the strong optical absorption band edge, ascribed to a charge transfer transition between Gd ions. A nonmonotonous change of refractive index with the increase of the Gd content indicates changes in the glass matrix and in Gd cluster structure.
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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Popov M. A.
Заглавие : Tree growth parameter in the Eden model on face-centered hypercubic lattices
Место публикации : Theor. Math. Phys. - 2005. - Vol. 144, Is. 3. - P.1361-1371. - ISSN 0040-5779, DOI 10.1007/s11232-005-0165-z
Примечания : Cited References: 19
Предметные рубрики: BRANCHED POLYMERS
HIGH-TEMPERATURES
EXPANSION
CLUSTERS
SYSTEMS
TIME
Ключевые слова (''Своб.индексиров.''): eden model--number of lattice trees--monte carlo method--growth parameter--singular points of generating function--large-dimension expansion--face-centered hypercubic lattice--eden model--face-centered hypercubic lattice--growth parameter--large-dimension expansion--monte carlo method--number of lattice trees--singular points of generating function
Аннотация: In the Eden model, we investigate how the tree growth parameter depends on the space dimension d for face-centered hypercubic lattices. We find the first three terms of the 1/d-expansion for this parameter directly from the generating function without calculating the number of trees because the growth parameter is the reciprocal coordinate of the singular point of the tree generating function. The same growth parameter was calculated by computer experiment where the ratios between the numbers of trees without intersections and trees without restrictions in the dimensions 3, 4, 6, 8, and 10 were estimated by the Monte Carlo method on face-centered cubic lattices. The results of the two methods agree well. Comparing with the previously performed computer experiment for simple hypercubic lattices, we observe that the values of the singular exponents for the tree generating functions are close for two different types of lattices.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sadreev A. F., Bulgakov E. N., Rotter I.
Заглавие : Trapping of an electron in the transmission through two quantum dots coupled by a wire
Место публикации : JETP Letters. - 2005. - Vol. 82, Is. 8. - P.498-503. - ISSN 0021-3640, DOI 10.1134/1.2150869
Примечания : Cited References: 32
Предметные рубрики: NUCLEAR REACTIONS
CIRCULAR BENDS
UNIFIED THEORY
WAVE-GUIDES
S-MATRIX
STATES
BILLIARD
SYSTEMS
Аннотация: We consider single-channel transmission through a double quantum dot that consists of two identical single dots coupled by a wire. The numerical solution for the scattering wave function shows that the resonance width of a few of the states may vanish when the width (or length) of the wire and the energy of the incident particle each take a certain value. In such a case, a particle is trapped inside the wire as the numerical visualization of the scattering wave function shows. To understand these numerical results, we explore a simple model with a small number of states, which allows us to consider the problem analytically. If the eigenenergies of the closed system cross the energies of the transmission zeroes, the wire effectively decouples from the rest of the system and traps the particle. (C) 2005 Pleiades Publishing, Inc.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : The study of magnetic properties of the quasi-one-dimensianal spin-1/2 antiferromagnet by Monte-Carlo method
Место публикации : Phys. Low-Dimens. Struct.: V S V CO. LTD, 2000. - Vol. 07.08.2013. - P37-46. - ISSN 0204-3467
Примечания : Cited References: 15
Предметные рубрики: ONE-DIMENSIONAL ANTIFERROMAGNETS
SYSTEMS
CHAINS
CA2CUO3
Аннотация: The thermodynamic quantities, two- and four-spin correlation functions as well as the correlation radius for weakly coupled antiferromagnetic spin chains with S = 1/2 are calculated using the mean-field approximation for the interchain coupling (J(2)) for longitudinal and transverse spin components by quantum Monte Carlo method. Results for the staggered magnetization and Neel temperature are in agreement with general scaling arguments. The value of triplet DeltaS(z) =1 gp in the spectrum of excitations is estimated. The transverse staggered field was found to induce an additional maximum in the correlation radius of the four spin correlation function around T/J(1) approximate to [0.05 divided by 0.075), J(2)/J(1) 0.03.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zinenko V. I., Zamkova N. G., Sofronova S. N.
Заглавие : The structural properties of RbMnX3 (X=F, Cl, Br) halides
Разночтения заглавия :авие SCOPUS: The structural properties of RbMnX3 (X = F, Cl, Br) halides
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2003. - Vol. 96, Is. 4. - P747-756. - ISSN 1063-7761, DOI 10.1134/1.1574547
Примечания : Cited References: 15
Предметные рубрики: POLARIZATION
SYSTEMS
Ключевые слова (''Своб.индексиров.''): crystals--formability--hydrostatic pressure--ions--phase transitions--polarization--rubidium compounds--cubic structures--hexagonal structures--quadrupole polarizabilities--structural properties--halogen compounds
Аннотация: The results of nonempirical calculation of energies of three polytypes (cubic, two-layer hexagonal, and six-layer hexagonal) are given for RbMnX3 (X=F, Cl, Br) crystals. The calculation is performed using an ionic crystal model with regard for the deformability and the dipole and quadrupole polarizabilities of ions. The behavior of these crystals under the action of hydrostatic pressure is studied. It is demonstrated that, at normal pressure, the RbMnCl3 and RbMnBr3 crystals have a six-layer hexagonal structure. At pressures above 11 kbar, RbMnCl3 passes to a phase with a cubic structure; RbMnBr3 at pressures above 90 kbar passes to a phase with a two-layer hexagonal structure. The RbMnF3 crystal under normal conditions has a cubic structure and experiences no phase transformations under the effect of pressure. The obtained results are in satisfactory agreement with the known experimental data. (C) 2003 MAIK "Nauka/Interperiodica".
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Mankov Y. I., Maradudin A. A.
Заглавие : The spectrum and damping of waves in partially randomized multilayers
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 1999. - Vol. 11, Is. 13. - P.2773-2790. - ISSN 0953-8984, DOI 10.1088/0953-8984/11/13/013
Примечания : Cited References: 24
Предметные рубрики: SPIN-WAVES
SEMICONDUCTOR SUPERLATTICES
LOCALIZATION
SYSTEMS
Аннотация: The spectrum and damping of waves in partially randomized multilayer structures are calculated. A method of calculation that was proposed and demonstrated earlier, for the model of a superlattice with a harmonic dependence of its material parameters along its axis in the initial state, is extended to the case of a multilayer structure (i.e., a superlattice with sharp interfaces). One- and three-dimensional random modulations of the period are considered, and the correlation function of the superlattice is derived as a series in which each term is a product of a harmonic and a monotonically decaying function. The law of decay of the correlation function is Gaussian for smooth inhomogeneities, and has different forms for one- and three-dimensional short-wavelength inhomogeneities. The spectrum and damping of waves in the superlattice described by this correlation function are found in the weak-coupling approximation in the vicinities of all of the odd Brillouin zone boundaries. Analytical dependences of the main characteristics of the spectrum and damping on the zone number n are obtained. The conditions for the closing of the gaps at the Brillouin zone boundaries are derived, and depend on the dimensionality of the inhomogeneities and the degree of their smoothness.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Val'kov V. V., Mitskan V. A., Korovushkin M. M.
Заглавие : The Kohn-Luttinger superconductivity in idealized doped graphene
Коллективы : Program of the Division of Physical Sciences of the Russian Academy of Sciences [11.3.1]; Russian Foundation for Basic Research [14-02-00058, 14-02-31237]; Council of the President of the Russian Federation [MK-526.2013.2]; Dynasty Foundation
Место публикации : Solid State Commun.: PERGAMON-ELSEVIER SCIENCE LTD, 2014. - Vol. 188. - P.61-66. - ISSN 0038-1098, DOI 10.1016/j.ssc.2014.03.001. - ISSN 1879-2766
Примечания : Cited References: 31. - This work was supported by the Program of the Division of Physical Sciences of the Russian Academy of Sciences (Project 11.3.1), and the Russian Foundation for Basic Research (Projects 14-02-00058 and 14-02-31237). One of the authors (M.M.K.) acknowledges the support of the Council of the President of the Russian Federation (Project MK-526.2013.2), and the Dynasty Foundation.
Предметные рубрики: REPULSIVE INTERACTIONS
HUBBARD-MODEL
SUPERFLUIDITY
INSTABILITY
MECHANISM
DENSITY
SYSTEMS
Ключевые слова (''Своб.индексиров.''): graphene--superconductivity
Аннотация: Idealized graphene monolayer is considered neglecting the van der Waals potential of the substrate and the role of the nonmagnetic impurities. The effect of the long-range Coulomb repulsion in an ensemble of Dirac fermions on the formation of the superconducting pairing in a monolayer is studied in the framework of the Kohn-Luttinger mechanism. The electronic structure of graphene is described in the strong coupling Wannier representation on the hexagonal lattice. We use the Shubin-Vonsowsky model which takes into account the intra- and intersite Coulomb repulsions of electrons. The Cooper instability is established by solving the Bethe-Salpeter integral equation, in which the role of the effective interaction is played by the renormalized scattering amplitude. The renormalized amplitude contains the Kohn-Luttinger polarization contributions up to and including the second-order terms in the Coulomb repulsion. We construct the superconductive phase diagram for the idealized graphene monolayer and show that the Kohn-Luttinger renormalizations and the intersite Coulomb repulsion significantly affect the interplay between the superconducting phases with f-, d+id-, and p+ip-wave symmetries of the order parameter. (C) 2014 Elsevier Ltd. All rights reserved.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Dzebisashvili D. M.
Заглавие : The electron energy spectrum and superconducting transition temperature of strongly correlated fermions with three-center interactions
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2005. - Vol. 100, Is. 3. - P608-616. - ISSN 1063-7761, DOI 10.1134/1.1901772
Примечания : Cited References: 29
Предметные рубрики: T-J MODEL
BAND HUBBARD-MODEL
VALENCE BOND STATE
RANGE-ORDER
SYSTEMS
WAVE
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--approximation theory--fermions--ground state--hamiltonians--superconductivity--density of states--electron energy spectrum--strongly correlated fermions--superconducting phase--superconducting transition temperature
Аннотация: The renormalizations of the fermionic spectrum are considered within the framework of the t-J* model taking into account three-center interactions (H-(3)) and magnetic fluctuations. Self-consistent spin dynamics equations for strongly correlated fermions with three-center interactions were obtained to calculate quasi-spin correlators. A numerical self-consistent solution to a system of ten equations was obtained to show that, in the nearest-neighbor approximation, simultaneously including H-(3) and magnetic fluctuations at n n(1) (n(1) approximate to 0.72 for 2t/U = 0.25) caused qualitative changes in the structure of the energy spectrum. A new Van Hove singularity is then induced in the density of states, and an additional maximum appears in the T-c(n) concentration dependence of the temperature of the transition to the superconducting phase with order parameter symmetry of the d(x2-y2) type. (C) 2005 Pleiades Publishing, Inc.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Zinenko V. I.
Заглавие : The effect of structural ordering on the magnetic, electronic, and optical properties of the LaPbMnSbO6 double perovskite
Коллективы : Russian Foundation for Basic Research [15-02-00340-a]; Russian Federation [NSH-924.2014.2]
Место публикации : J. Alloys Compd.: Elsevier Science, 2016. - Vol. 671. - P.184-191. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2016.02.085. - ISSN 1873-4669(eISSN)
Примечания : Cited References:32. - This work was supported by the Russian Foundation for Basic Research, project no. 15-02-00340-a and the Grant of the President of the Russian Federation for Support of Leading Scientific Schools no. NSH-924.2014.2.
Предметные рубрики: SYSTEMS
NI
CO
Ключевые слова (''Своб.индексиров.''): ab initio calculation--double perovskite--magnetic materials--optical--properties--electronic properties--magnetic properties--layer compound
Аннотация: The interplay between the magnetic, electronic, and optical properties and the cation structural ordering in the LaPbMnSbO6 double perovskite is studied using the Vienna Ab Initio Simulation Package (VASP). The layer and rock-salt cation ordering types are investigated. Both of them are of great importance. The rock-salt ordering of B-site cations is one of the most frequently met cation ordering types in double perovskites; the layer ordering of both cations, which can be considered as a heterostructure, is interesting for fundamental research and experimental synthesis. It was established that the properties of the two investigated structures are strongly different. The compound with the layered structure exhibits the behavior typical of a semimetal with the ferromagnetic configuration of magnetic moments, which is unusual for a double perovskite. The rock-salt structure behaves as an antiferromagnetic insulator. Another surprising feature of the structure with the layer ordering is the coexistence of a polar phase and the metal-type conductivity. The calculated optical characteristics of the two ordered structures are compared with the experimental dates. (C) 2016 Elsevier B.V. All rights reserved.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E.
Заглавие : THE critical exponent of the tree lattice generating function in the eden model
Разночтения заглавия :авие SCOPUS: The critical exponent of the tree lattice generating function in the eden model
Место публикации : Theor. Math. Phys.: SPRINGER, 2010. - Vol. 165, Is. 2. - P1443-1455. - ISSN 0040-5779, DOI 10.1007/s11232-010-0120-5
Примечания : Cited References: 14
Предметные рубрики: GROWTH PARAMETER
CLUSTERS
DIMENSIONS
SYSTEMS
Ключевые слова (''Своб.индексиров.''): number of lattice trees--tree perimeter--generating function--critical exponent--hypercubic lattice--bethe lattice--eden model--bethe lattice--critical exponent--eden model--generating function--hypercubic lattice--number of lattice trees--tree perimeter
Аннотация: We consider the increase in the number of trees as their size increases in the Eden growth model on simple and face-centered hypercubic lattices in different space dimensions. We propose a first-order partial differential equation for the tree generating function, which allows relating the exponent at the critical point of this function to the perimeter of the most probable tree. We estimate tree perimeters for the lattices considered. The theoretical values of the exponents agree well with the values previously obtained by computer modeling. We thus explain the closeness of the dimension dependences of the exponents of the simple and face-centered lattices and their difference from the results in the Bethe lattice approximation.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Alekseev K. N., Perina J.
Заглавие : The 1/N-expansion, quantum-classical correspondence and nonclassical states generation in dissipative higher-order anharmonic oscillators
Место публикации : Phys. Scr.: ROYAL SWEDISH ACAD SCIENCES, 2000. - Vol. 61, Is. 1. - P7-16. - ISSN 0281-1847, DOI 10.1238/Physica.Regular.061a00007
Примечания : Cited References: 38
Предметные рубрики: 2ND-HARMONIC GENERATION
HARMONIC-GENERATION
SQUEEZED STATES
CHAOS
LIGHT
MECHANICS
DYNAMICS
STATISTICS
SYSTEMS
OPTICS
Аннотация: We develop a method for the determination of the dynamics of dissipative quantum systems in the limit of large number of quanta N, based on the 1/N-expansion of Heidmann et al. [Opt. Commun. 54, 189 (1985)] and the quantum-classical correspondence. Using this method, we End analytically the dynamics of nonclassical states generation in the higher-order anharmonic dissipative oscillators for an arbitrary temperature of a reservoir. We show that the quantum correction to the classical motion increases with time quadratically up to some maximal value, which is dependent on the degree of nonlinearity and a damping constant, and then it decreases. Similarities and differences with the corresponding behavior of the quantum corrections to the classical motion in the Hamiltonian chaotic systems are discussed. We also compare our results obtained for some limiting cases with the results obtained by using other semiclassical tools and discuss the conditions for validity of our approach.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Isohatala J., Alekseev K. N., Kurki L. T., Pietilainen P.
Заглавие : Symmetry breaking in a driven and strongly damped pendulum
Место публикации : Phys. Rev. E: AMERICAN PHYSICAL SOC, 2005. - Vol. 71, Is. 6. - Ст.66206. - ISSN 1539-3755, DOI 10.1103/PhysRevE.71.066206
Примечания : Cited References: 37
Предметные рубрики: DC VOLTAGE GENERATION
SEMICONDUCTOR SUPERLATTICES
JOSEPHSON-JUNCTIONS
BLOCH OSCILLATIONS
FORCED PENDULUM
CHAOS
FREQUENCY
SYSTEMS
RECTIFICATION
STANDARD
Ключевые слова (''Своб.индексиров.''): periodically driven pendulums--symmetry breaking--bifurcation (mathematics)--damping--dynamics--nonlinear systems--semiconductor superlattices--pendulums
Аннотация: We examine the conditions for appearance of a symmetry breaking bifurcation in damped and periodically driven pendulums in the case of strong damping. We show that symmetry breaking, unlike other nonlinear phenomena, can exist at high dissipation. We prove that symmetry breaking phases exist between phases of symmetric normal and symmetric inverted oscillations. We find that symmetry broken solutions occupy a smaller region of the pendulum's parameter space in comparison to the statements made in earlier considerations [McDonald and Plischke, Phys. Rev. B 27, 201 (1983)]. Our research on symmetry breaking in a strongly damped pendulum is relevant to an understanding of the phenomena of dynamic symmetry breaking and rectification in pure ac driven semiconductor superlattices.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Sadreev A. F.
Заглавие : Statistics of wave functions and currents induced by spin-orbit interaction in chaotic billiards
Место публикации : Phys. Rev. E: AMER PHYSICAL SOC, 2004. - Vol. 70, Is. 5. - Ст.56211. - ISSN 1539-3755, DOI 10.1103/PhysRevE.70.056211
Примечания : Cited References: 33
Предметные рубрики: HELMHOLTZ-EQUATION
PERSISTENT CURRENTS
ELECTRON-GAS
RINGS
EIGENFUNCTIONS
SYSTEMS
PHASE
Ключевые слова (''Своб.индексиров.''): approximation theory--chaos theory--degrees of freedom (mechanics)--eigenvalues and eigenfunctions--electric field effects--electric potential--electron gas--hamiltonians--heterojunctions--microwaves--statistical methods--chaotic robnik billiards--current distributions--spin-orbit interaction (soi)--wave functions--quantum theory
Аннотация: We show that the wave function and current statistics in chaotic Robnik billiards crucially depend on the constant of the spin-orbit interaction (SOI). For small constant the current statistics is described by universal current distributions derived for slightly opened chaotic billiards [Saichev et al. J. Phys. A. 35, L87 (2002)] although one of the components of the spinor eigenfunctions is not universal. For strong SOI both components of the spinor eigenstate are complex random Gaussian fields. This observation allows us to derive the distributions of spin-orbit persistent cut-rents which well describe numerical statistics. For intermediate values of the statistics of the eigenstates and currents, both are deeply nonuniversal.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Static and dynamic magnetic properties of coupled spin-1/2 antiferromagnetic chains
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2000. - Vol. 12, Is. 37. - P.8191-8207. - ISSN 0953-8984, DOI 10.1088/0953-8984/12/37/316
Примечания : Cited References: 21
Предметные рубрики: ONE-DIMENSIONAL ANTIFERROMAGNETS
SYSTEMS
SUSCEPTIBILITY
EXCITATIONS
SR2CUO3
CA2CUO3
KCUF3
Ключевые слова (''Своб.индексиров.''): computational methods--copper compounds--correlation methods--functions--magnetic field effects--magnetic properties--magnetization--monte carlo methods--quantum theory--specific heat--thermal effects--excitation spectroscopy--interchain coupling--intrachain couplings--mean-field approximation--spin-spin correlation function--spinons--antiferromagnetic materials
Аннотация: Calculations of the thermodynamic quantities, and the spectra of spinons, triplet excitations, and two-particle spin-singlet (Delta S-z = 0, +/- 1) excitations for a weakly coupled antiferromagnetic S = 1/2 spin chain are made using a mean-field approximation for the interchain couplings (J(2)) by the quantum Monte Carlo method. The mass gaps in these excitation spectra are estimated as functions of the interchain coupling. The critical held H-c, and the temperatures at which the spinon and singlet gaps close (T-1 and T-2, respectively) are obtained. Some peculiarities of the staggered magnetization, the specific heat, and the spin-spin correlation function are found at T-1 = 0.9J(2), T-2 = 1.5J(2), H-c = 3.8J(2), as determined by linear function fitting for J(2)/J(1) 0.15 The intrachain and interchain couplings, and the staggered magnetization for KCuF3, Sr2CuO3, and Ca2CuO3 are estimated, and mass gaps are predicted to exist in the spectra of the spinons and the singlet two-particle excitations.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Alekseev K. N., Priimak D. S.
Заглавие : Squeezed states and quantum chaos
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 1998. - Vol. 86, Is. 1. - P61-70. - ISSN 1063-7761, DOI 10.1134/1.558469
Примечания : Cited References: 41
Предметные рубрики: PERIODICALLY KICKED PENDULUM
CLASSICAL CORRESPONDENCE
SYSTEMS
LIGHT
FLUCTUATIONS
OSCILLATOR
MECHANICS
MASER
Аннотация: We examine the dynamics of a wave packet that initially corresponds to a coherent state in the model of a quantum rotator excited by a periodic sequence of kicks. This model is the main model of quantum chaos and allows for a transition from regular behavior to chaotic in the classical limit. By doing a numerical experiment we study the generation of squeezed states in quasiclassical conditions and in a time interval when quantum-classical correspondence is well-defined. We find that the degree of squeezing depends on the degree of local instability in the system and increases with the Chirikov classical stochasticity parameter. We also discuss the dependence of the degree of squeezing on the initial width of the packet, the problem of stability and observability of squeezed states in the transition to quantum chaos, and the dynamics of disintegration of wave packets in quantum chaos. (C) 1998 American Institute of Physics.
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