Communications in Theoretical Physics 2013 Vol.60
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Approximate Bound States Solution of the Hellmann Potential
M. Hamzavi, K.E. Thylwe, A.A. Rajabi
Communications in Theoretical Physics    2013, 60 (01): 1-8.  
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The Hellmann potential, which is a superposition of an attractive Coulomb potential -a/r and a Yukawa potential b e-δr/r, is often used to compute bound-state normalizations and energy levels of neutral atoms. By using the generalized parametric Nikiforov-Uvarov (NU) method, we have obtained the approximate analytical solutions of the radial Schrödinger equation (SE) for the Hellmann potential. The energy eigenvalues and corresponding eigenfunctions are calculated in closed forms. Some numerical results are presented, which show good agreement with a numerical amplitude phase method and also those previously obtained by other methods. As a particular case, we find the energy levels of the pure Coulomb potential.
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Klein Gordon Oscillators in Commutative and Noncommutative Phase Space with Psudoharmonic Potential in the Presence and Absence Magnetic Field
H. Hassanabadi, S.S. Hosseini, Z. Molaee
Communications in Theoretical Physics    2013, 60 (01): 9-18.  
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We study the Klein-Gordon oscillator in commutative, noncommutative space, and phase space with psudoharmonic potential under magnetic field hence the other choice is studying the Klein-Gordon equation oscillator in the absence of magnetic field. In this work, we obtain energy spectrum and wave function in different situations by NU method so we show our results in tables.
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Quantum Interference of Dual-Channel Excited Magnons in Spin-1 Bose-Einstein Condensates Atomic Chain
ZHAO Xu, ZHAO Xing-Dong, ZHOU Lu, JING Hui, ZHANG Wei-Ping
Communications in Theoretical Physics    2013, 60 (01): 19-24.  
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We investigate the quantum interference of spin wave excitations of a spin-1 atomic Bose condensate confined in an optical lattice. Single-channel and dual-channel interactions are employed in our system, and their induced excitations are compared. Also we consider the interplay of magneto-optical excitations, which leads to a constructive or destructive effect for the creation of magnons based on background excitations. The population distributions of excited magnons can be well controlled by steering the long-range dipole-dipole interactions. Such a scheme can be used to demonstrate conventional quantum-optical phenomena like dynamical Casimir effect at finite temperatures.
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Scattering States of Schrödinger Equation under the Modified Cusp Potential
Z. Molaee, H. Hassanabadi, S. Zarrinkamar
Communications in Theoretical Physics    2013, 60 (01): 25-27.  
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We solve the one-dimensional time-independent Schrödinger equation in the presence of the modified Cusp potential and report the solutions in terms of the Whittaker functions. We obtain the reflection and transmission coefficients as well as the bound-state solutions in terms of the Whittaker functions. We comment on the solutions and discuss them in terms of the engaged parameters.
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Thermodynamics of the Apparent Horizon in FRW Universe with Massive Gravity
LI Hui, ZHANG Yi
Communications in Theoretical Physics    2013, 60 (01): 28-36.  
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Applying Clausius relation with energy-supply defined by the unified first law of thermodynamics formalism to the apparent horizon of a massive gravity model in cosmology proposed lately, the corrected entropic formula of the apparent horizon is obtained with the help of the modified Friedmann equations. This entropy-area relation, together with the identified Misner-Sharp internal energy, verifies the first law of thermodynamics for the apparent horizon with a volume change term for consistency. On the other hand, by means of the corrected entropy-area formula and the Clausius relation δQ=T dS, where the heat flow δQ is the energy-supply of pure matter projecting on the vector ζ tangent to the apparent horizon and should be looked on as the amount of energy crossing the apparent horizon during the time interval dt and the temperature of the apparent horizon for energy crossing during the same interval is 1/2πrA, the modified Friedmann equations governing the dynamical evolution of the universe are reproduced with the known energy density and pressure of massive graviton. The integration constant is found to correspond to a cosmological term which could be absorbed into the energy density of matter. Having established the correspondence of massive cosmology with the unified first law of thermodynamics on the apparent horizon, the validity of the generalized second law of thermodynamics is also discussed by assuming the thermal equilibrium between the apparent horizon and the matter field bounded by the apparent horizon. It is found that, in the limit Hc→0, which recovers the Minkowski reference metric solution in the flat case, the generalized second law of thermodynamics holds if α3+4α4<0. Without this condition, even for the simplest model of dRGT massive cosmology with α34=0, the generalized second law of thermodynamics could be violated.
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Some Analytical Properties of the Model for Stochastic Evolutionary Games in Finite Populations with Non-uniform Interaction Rate
QUAN Ji, WANG Xian-Jia
Communications in Theoretical Physics    2013, 60 (01): 37-47.  
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Traditional evolutionary games assume uniform interaction rate, which means that the rate at which individuals meet and interact is independent of their strategies. But in some systems, especially biological systems, the players interact with each other discriminately. Taylor and Nowak (2006) were the first to establish the corresponding non-uniform interaction rate model by allowing the interaction rates to depend on strategies. Their model is based on replicator dynamics which assumes an infinite size population. But in reality, the number of individuals in the population is always finite, and there will be some random interference in the individuals' strategy selection process. Therefore, it is more practical to establish the corresponding stochastic evolutionary model in finite populations. In fact, the analysis of evolutionary games in a finite size population is more difficult. Just as Taylor and Nowak said in the outlook section of their paper, "The analysis of non-uniform interaction rates should be extended to stochastic game dynamics of finite populations." In this paper, we are exactly doing this work. We extend Taylor and Nowak's model from infinite to finite case, especially focusing on the influence of non-uniform connection characteristics on the evolutionary stable state of the system. We model the strategy evolutionary process of the population by a continuous ergodic Markov process. Based on the limit distribution of the process, we can give the evolutionary stable state of the system. We make a complete classification of the symmetric 2×2 games. For each case game, the corresponding limit distribution of the Markov-based process is given when noise intensity is small enough. In contrast with most literatures in evolutionary games using the simulation method, all our results obtained are analytical. Especially, in the dominant-case game, coexistence of the two strategies may become evolutionary stable states in our model. This result can be used to explain the emergence of cooperation in the Prisoner is Dilemma Games to some extent. Some specific examples are given to illustrate our results.
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The Stability of Multi-modal Traffic Network
HAN Ling-Hui, Sun Hui-Jun, ZHU Cheng-Juan, WU Jian-Jun, JIA Bin
Communications in Theoretical Physics    2013, 60 (01): 48-54.  
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There is an explicit and implicit assumption in multimodal traffic equilibrium models, that is, if the equilibrium exists, then it will also occur. The assumption is very idealized; in fact, it may be shown that the quite contrary could happen, because in multimodal traffic network, especially in mixed traffic conditions the interaction among traffic modes is asymmetric and the asymmetric interaction may result in the instability of traffic system. In this paper, to study the stability of multimodal traffic system, we respectively present the travel cost function in mixed traffic conditions and in traffic network with dedicated bus lanes. Based on a day-to-day dynamical model, we study the evolution of daily route choice of travelers in multimodal traffic network using 10000 random initial values for different cases. From the results of simulation, it can be concluded that the asymmetric interaction between the cars and buses in mixed traffic conditions can lead the traffic system to instability when traffic demand is larger. We also study the effect of travelers' perception error on the stability of multimodal traffic network. Although the larger perception error can alleviate the effect of interaction between cars and buses and improve the stability of traffic system in mixed traffic conditions, the traffic system also become instable when the traffic demand is larger than a number. For all cases simulated in this study, with the same parameters, traffic system with dedicated bus lane has better stability for traffic demand than that in mixed traffic conditions. We also find that the network with dedicated bus lane has higher portion of travelers by bus than it of mixed traffic network. So it can be concluded that building dedicated bus lane can improve the stability of traffic system and attract more travelers to choose bus reducing the traffic congestion.
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Light Front Fermion Model Propagation
Jorge Henrique Sales, Alfredo Takashi Suzuki
Communications in Theoretical Physics    2013, 60 (01): 55-68.  
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In this work we consider the propagation of two fermion fields interacting with each other by the exchange of intermediate scalar bosons in the light front. We obtain the corrections up to fourth order in the coupling constant using hierarchical equations in order to obtain the bound state equation (Bethe-Salpeter equation).
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Reanalysis of Elastic Scattering of 6Li + 209Bi Reaction Using a New Density Distribution of 6Li Nucleus
M. Aygun
Communications in Theoretical Physics    2013, 60 (01): 69-72.  
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In the present paper, the elastic scattering of 6Li + 209Bi system is reanalyzed by using the double folding model (DFM) at energies near the Coulomb barrier (ELab=29.9 and 32.8 MeV). With this goal, a new density distribution of 6Li nucleus, the no-core full configuration (NCFC) density distribution (DD), is used to obtain the real potentials in DFM calculations. The NCFC DD results are compared with the results of both gaussian shape (GS) DD and an earlier study as well as the experimental data. This comparison provides information about the similarities and differences of the models used in calculations.
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High-Order Dispersion Coefficients for Alkali-metal Atoms
KANG Shuai, DING Chi-Kun, CHEN Chang-Yong, WU Xue-Qing
Communications in Theoretical Physics    2013, 60 (01): 73-79.  
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High-order dispersion coefficients C9, C11, C12, and C13 for the ground-state alkali-metals were calculated by combining the l-dependent model potential of alkali-metal atoms and linear variation method based on B-spline basis functions. The results were compared.
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Properties of Defect Modes in Periodic Lossy Multilayer with Negative-Index-Materials
Alireza Aghajamali, Mahmood Barati
Communications in Theoretical Physics    2013, 60 (01): 80-86.  
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Employing the characteristic matrix method, this study investigates transmission properties of one-dimensional defective lossy photonic crystals composed of negative and positive refractive index layers with one lossless defect layer at the center of the crystal. The results of the study show that as the refractive index and thickness of the defect layer increase, the frequency of the defect mode decreases. In addition, the study shows that the frequency of the defect mode is sensitive to the incidence angle, polarization, and physical properties of the defect layer, but it is insensitive to the small lattice loss factor. The peak of the defect mode is very sensitive to the loss factor, incidence angle, polarization, refractive index, and thickness of the defect layer. This study also shows that the peak and the width of the defect mode are affected by the numbers of the lattice period and the loss factor. The results can lead to designing new types of narrow filter structures and other optical devices.
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Control of Wave Propagation and Effect of Kerr Nonlinearity on Group Index
Hazrat Ali, Ziauddin, Iftikhar Ahmed
Communications in Theoretical Physics    2013, 60 (01): 87-92.  
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We use four-level atomic system and control the wave propagation via forbidden decay rate. The Raman gain process becomes dominant on electromagnetically induced transparency (EIT) medium by increasing the forbidden decay rate via increasing the number of atoms [G.S. Agarwal and T.N. Dey, Phys. Rev. A 74 (2005) 043805 and K. Harada, T. Kanbashi, and M. Mitsunaga, Phys. Rev. A 73 (2006) 013803]. The behavior of wave propagation is dramatically changed from normal (subluminal) to anomalous (superluminal) dispersion by increasing the forbidden decay rate. The system can also give a control over the group velocity of the light propagating through the medium via Kerr field.
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Modulational Instability in a Pair of Non-identical Coupled Nonlinear Electrical Transmission Lines
Eric Tala-Tebue, Aurelien Kenfack-Jiotsa, Marius Hervé Tatchou-Ntemfack, Timoléon Crépin Kofané
Communications in Theoretical Physics    2013, 60 (01): 93-100.  
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In this work, we investigate the dynamics of modulated waves non-identical coupled nonlinear transmission lines. Traditional methods for avoiding mode mixing in identical coupled nonlinear electrical lines consist of adding the same number of linear inductors in each branch. Adding linear inductors in a single line leads to asymmetric coupled nonlinear electrical transmission lines which propagate the signal and the mode mixing. On one hand, the difference between the two lines induced the fission for only one mode of propagation. This fission is influenced by the amplitude of the signal and the amount of the input energy as well; it also narrows the width of the input pulse soliton, leading to a possible increasing of the bit rate. On the other hand, the dissymmetry of the two lines converts the network into a good amplifier for the ω_ mode which corresponds to the regime admitting low frequencies.
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Brittle-Ductile Transition of Ferroelectric Ceramics Induced by Thermally Activated Dislocation Emission
XIE Chao, FANG Qi-Hong, LIU You-Wen, CHEN Jian-Kang, MA Ting-Feng
Communications in Theoretical Physics    2013, 60 (01): 101-107.  
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Thermally activated dislocation emission in high-temperature ferroelectric ceramics is investigated through an assumption of thermal stability and a novel analytical method. The stress intensity factor (SIF) arising from domain switching is evaluated by using a Green's function method, and the critical applied electric field intensity factor (CAEFIF) for brittle fracture at room temperature is obtained. Besides, the lowest temperature for single dislocation emission before brittle fracture is also obtained by constructing an energy balance. The multi-scale analysis of facture toughness of the ferroelectric ceramics at high temperature is carried out. Through the analysis, the CAEFIF for crack extension is recalculated. The results show that the competition and interaction effects between dislocation emission and brittle fracture are very obvious. Besides, the higher critical activation temperature, the more columns of obstacles will be overcome. Additionally, the shielding effect arising from thermally activated dislocations is remarkable, thus, the brittle-ductile transition can promote the fracture toughness of high-temperature ferroelectric ceramics.
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Effects of Isotopic Concentrations on Thermodynamic Parameters of Deuterium-Tritium Mixtures
S.M. Motevalli, M.R. Pahlavani, M. Azimi
Communications in Theoretical Physics    2013, 60 (01): 108-112.  
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Thermodynamic estimation is still too much requested for scientific applications in spite of great advances in simulation methods for efficient determination of phase equilibrium of multi-component systems. In this work, thermodynamic properties of deuterium-tritium mixture in a wide range of temperatures and pressures have been predicted. Buckingham exp-6 potential has been utilized in calculations, based on statistical perturbation theory. The effects of various values of density, temperature and isotopic concentrations on pressure have been studied. Eventually, we have found out symmetrical effects of tritium concentration in deuterium-tritium mixtures.
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Working Mechanism of a BC3 Nanotube Carbon Monoxide Gas Sensor
Ali Ahmadi Peyghan, Sirous Yourdkhani, Maziar Noei
Communications in Theoretical Physics    2013, 60 (01): 113-118.  
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Carbon and BN nanotubes have previously demonstrated extreme sensitivity to several molecules, but they cannot be used to detect highly toxic molecules of CO. In this work, we examine the possibility of a BC3 nanotube (BC3NT) as a potential gas sensor for CO detection by using density functional theory calculations. It is found that CO molecule can be absorbed on B and C atoms of BC3NT wall with adsorption energies in the range of -1.0 to -25.9 kcal/mol and it can donate finite charge to the tube. By comparing the HOMO/LUMO energy gaps of the bare and CO adsorbed nanotubes, we deduce that molecular CO can induce significant change in the electrical conductivity of the tube. The conductivity change can generate an electrical signal, which might be useful for CO detection.
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Dependence of Spin-orbit Parameters in AlxGa1-xN/GaN Quantum Wells on the Al Composition of the Barrier
Li Ming
Communications in Theoretical Physics    2013, 60 (01): 119-123.  
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In this paper, we obtain considerable spin-orbit (SO) parameters in AlxGa1-xN/GaN quantum wells (QWs) with sheet carrier concentration Ns =120×10 11/cm2. With increasing Al content (x) of the barrier, the SO parameters increase as a whole, and the two major contributions are found to be the decrease of the expansion region of the envelope functions and the increase of the polarized electric field in the well. Compared with the Rashba parameters for the first two subbands, the intersubband SO parameter is a bit smaller and varies more slowly with x. The results indicate the SO parameters, especially the Rashba parameters can be engineered by the Al composition of the barrier, which may be helpful to the spin manipulation of III-nitride low-dimensional heterostructures.
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Donor Binding Energy in GaAs/Ga1-x AlxAs Quantum Well: the Laser Field and Temperature Effects
WEI Shu-Yi, HOU Wen-Xiu, CHEN Xiao-Yang, XIA Cong-Xin
Communications in Theoretical Physics    2013, 60 (01): 124-128.  
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Based on the effective-mass approximation theory and variational method, the laser field and temperature effects on the ground-state donor binding energy in the GaAs/Ga1-xAlxAs quantum well (QW) are investigated. Numerical results show that the donor binding energy depends on the impurity position, laser parameter, temperature, Al composition, and well width. The donor binding energy is decreased when the laser field and temperature are increased in the QW for any impurity position and QW parameter case. Moreover, the laser field has an obvious influence on the donor binding energy of impurity located at the vicinity of the QW center. In addition, our results also show that the donor binding energy decreases (or increases) as the well width (or Al composition x) increases in the QW.
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Topological Insulators on the Ruby Lattice with Rashba Spin-Orbit Coupling
HOU Jing-Min, WANG Guo-Xiang
Communications in Theoretical Physics    2013, 60 (01): 129-135.  
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We investigate a tight-binding model of the ruby lattice with Rashba spin-orbit coupling. We calculate the band structure of the lattice and evaluate the Z2 topological indices. According to the Z2 topological indices and the band structure, we present the phase diagrams of the lattice with different filling fractions. We find that topological insulators occur in some range of parameters at 1/6, 1/3, 1/2, 2/3 and 5/6 filling fractions. We analyze and discuss the characteristics of these topological insulators and their edge states.
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A Theoretical Model to Explain the Mechanism of Electromagnetic Wave Propagation Along Cylindrical Micelles
Afshin Moradi
Communications in Theoretical Physics    2013, 60 (01): 136-138.  
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A theoretical model to explain the mechanism of the electromagnetic wave propagation in the quasi two-dimensional layer of counterions adjacent to the surface of a charged cylindrical membrane is presented. By using Maxwell and hydrodynamic equations with appropriate boundary conditions, general expression of dispersion relation is obtained for the electromagnetic wave with mixed TE and TM modes.
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Reliability and Efficiency of Generalized Rumor Spreading Model on Complex Social Networks
Yaghoob Naimi, Mohammad Naimi
Communications in Theoretical Physics    2013, 60 (01): 139-144.  
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We introduce the generalized rumor spreading model and investigate some properties of this model on different complex social networks. Despite pervious rumor models that both the spreader-spreader (SS) and the spreader-stifler (SR) interactions have the same rate α, we define α(1) and α(2) for SS and SR interactions, respectively. The effect of variation of α(1) and α(2) on the final density of stiflers is investigated. Furthermore, the influence of the topological structure of the network in rumor spreading is studied by analyzing the behavior of several global parameters such as reliability and efficiency. Our results show that while networks with homogeneous connectivity patterns reach a higher reliability, scale-free topologies need a less time to reach a steady state with respect the rumor.
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Generating a New Higher-Dimensional Coupled Integrable Dispersionless System: Algebraic Structures, Bäcklund Transformation and Hidden Structural Symmetries
Souleymanou Abbagari, Thomas B. Bouetou, Timoleon C. Kofane
Communications in Theoretical Physics    2013, 60 (02): 145-149.  
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The prolongation structure methodologies of Wahlquist-Estabrook [H.D. Wahlquist and F.B. Estabrook, {J. Math. Phys.} 16 (1975) 1] for nonlinear differential equations are applied to a more general set of coupled integrable dispersionless system. Based on the obtained prolongation structure, a Lie-Algebra valued connection of a closed ideal of exterior differential forms related to the above system is constructed. A Lie-Algebra representation of some hidden structural symmetries of the previous system, its Bäcklund transformation using the Riccati form of the linear eigenvalue problem and their general corresponding Lax-representation are derived. In the wake of the previous results, we extend the above prolongation scheme to higher-dimensional systems from which a new (2+1)-dimensional coupled integrable dispersionless system is unveiled along with its inverse scattering formulation, which applications are straightforward in nonlinear optics where additional propagating dimension deserves some attention.
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Dynamics of the Manakov Solitons in Biased Guest-Host Photorefractive Polymer
TAN Zhao, TIAN Bo, JIANG Yan, WANG Pan, LI Min
Communications in Theoretical Physics    2013, 60 (02): 150-158.  
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In the biased guest-host photorefractive polymer, the Manakov equations can be used to describe the optical soliton propagation and interaction. Hereby for such equations, via the Hirota method and symbolic computation, analytic soliton solutions in the bright-dark and dark-dark forms are obtained. Based on the choice of photorefractive polymer parameter and incident-optical-beam parameter, the bright-dark and dark-dark solitons as well as their interaction can occur in the polymer when the total intensity is much lower than the background illumination, and our analysis indicates that the incident light with different polarization directions influence little on the soliton propagation. γ, representing the soliton intensity far away from the soliton center, determines the appearance of bright or dark soliton under the background illumination. Through the graphic and asymptotic analysis on the two-soliton solutions along with the different γ, we find that there exist the elastic and inelastic interactions between the bright-dark solitons, while the interactions between the dark-dark solitons are always elastic.
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Adomian Decomposition Method Using Integrating Factor
Yinwei Lin, Tzon-Tzer Lu, Cha'o-Kuang Chen
Communications in Theoretical Physics    2013, 60 (02): 159-164.  
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This paper proposes a new Adomian decomposition method by using integrating factor. Nonlinear models are solved by this method to get more reliable and efficient numerical results. It can also solve ordinary differential equations where the traditional one fails. Besides, the complete error analysis for this method is presented.
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Single-Qubit Operation Sharing with Bell and W Product States
JI Qi-Bin, LIU Yi-Min, LIU Xian-Song, YIN Xiao-Feng, ZHANG Zhan-Jun
Communications in Theoretical Physics    2013, 60 (02): 165-170.  
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Two tripartite schemes are put forward with shared entanglements and Local Operation and Classical Communication (LOCC) for sharing an operation on a remote target sate. The first scheme uses a Bell and a symmetric W states as quantum channels, while the second replaces the symmetric W state by an asymmetric one. Both schemes are treated and compared from the aspects of quantum resource consumption, operation complexity, classical resource consumption, success probability and efficiency. It is found that the latter scheme is better than the former one. Particularly, the sharing can be achieved only probabilistically with the first scheme deterministically with the second one.
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Effects of Quantum Correction on Dynamical Phase Transition in a Single Species Bosonic Josephson Junction
TIAN Jing, QIU Hai-Bo
Communications in Theoretical Physics    2013, 60 (02): 171-174.  
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In this paper, by employing Bogliubov backreaction method, we investigate quantum correction effects on dynamical phase transition in a single species bosonic Josephson junction induced by increasing nonlinear interaction. Compared with mean field theory results, we find that the transition point is shifted. The dynamical phase transition is accompanied by a change of the entanglement entropy, which is found to reach a maximum at the transition point of the mean field theory.
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Painlevé Analysis, Lie Symmetries and Exact Solutions for Variable Coefficients Benjamin-Bona-Mahony-Burger (BBMB) Equation
Vikas Kumar, R.K. Gupta, Ram Jiwari
Communications in Theoretical Physics    2013, 60 (02): 175-182.  
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In this paper, a variable-coefficient Benjamin-Bona-Mahony-Burger (BBMB) equation arising as a mathematical model of propagation of small-amplitude long waves in nonlinear dispersive media is investigated. The integrability of such an equation is studied with Painlevé analysis. The Lie symmetry method is performed for the BBMB equation and then similarity reductions and exact solutions are obtained based on the optimal system method. Furthermore different types of solitary, periodic and kink waves can be seen with the change of variable coefficients.
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Reconstruction of Scalar Field Dark Energy Models in Kaluza-Klein Universe
M. Sharif, Abdul Jawad
Communications in Theoretical Physics    2013, 60 (02): 183-188.  
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This paper is devoted to study the modified holographic dark energy model by taking its different aspects in the flat Kaluza-Klein universe. We construct the equation of state parameter which evolutes the universe from quintessence region towards the vacuum. It is found that the modified holographic model exhibits instability against small perturbations in the early epoch of the universe but becomes stable in the later times. We also develop its correspondence with some scalar field dark energy models. It is interesting to mention here that all the results are consistent with the present observations.
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Finite-Time Stability of Fractional-Order Neural Networks with Delay
WU Ran-Chao, HEI Xin-Dong, CHEN Li-Ping
Communications in Theoretical Physics    2013, 60 (02): 189-193.  
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Finite-time stability of a class of fractional-order neural networks is investigated in this paper. By Laplace transform, the generalized Gronwall inequality and estimates of Mittag-Leffler functions, sufficient conditions are presented to ensure the finite-time stability of such neural models with the Caputo fractional derivatives. Furthermore, results about asymptotical stability of fractional-order neural models are also obtained.
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Darboux Transformation and Soliton Solutions for the (2+1)-Dimensional Generalization of Shallow Water Wave Equation with Symbolic Computation
WEN Xiao-Yong, MENG Xiang-Hua
Communications in Theoretical Physics    2013, 60 (02): 194-200.  
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In this paper, the (2+1)-dimensional generalization of shallow water wave equation, which may be used to describe the propagation of ocean waves, is analytically investigated. With the aid of symbolic computation, we prove that the (2+1)-dimensional generalization of shallow water wave equation possesses the Painlevé property under a certain condition, and its Lax pair is constructed by applying the singular manifold method. Based on the obtained Lax representation, the Darboux transformation (DT) is constructed. The first iterated solution, second iterated solution and a special N-soliton solution with an arbitrary function are derived with the resulting DT. Relevant properties are graphically illustrated, which might be helpful to understanding the propagation processes for ocean waves in shallow water.
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The Effects of Simplest Little Higgs Model on the Spin Correlations in the Top Quark Pair Production at the LHC and ILC
HAN Xiao-Fang, SHI Wen-Pu, WANG Lei
Communications in Theoretical Physics    2013, 60 (02): 201-204.  
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In the simplest little Higgs model (SLH), we study the spin correlations in the top quark pair production at the LHC and ILC. We find that the SLH always suppresses the tt spin correlations compared to the SM values. At the LHC, the suppression can be over 10% for mZ' < 750 GeV. The SLH prediction value is outside the 1σ range of the experimental data from ATLAS, and within 1σ range of the experimental data from CMS. At the ILC, the SLH can sizably suppress the tt spin correlation for mZ' approaching the center-of-mass energy √s. For example, the maximal suppression can reach -22.5%, -14.5%, and -9.5% for √s=500 GeV, 800 GeV, and 1000 GeV, respectively. Therefore, the tt spin correlation at the ILC can be a sensitive probe for the SLH.
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Detection of Charged Higgs Bosons in e+e-(γγ)→tbφ- Production at the ILC
HAN Jin-Zhong, LI Bing-Zhong
Communications in Theoretical Physics    2013, 60 (02): 205-209.  
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In the context of the left-right twin Higgs (LRTH) model, we have studied the charged Higgs bosons production processes e+e-(γγ)→tbφ- at the International Linear Collider (ILC). It is found that the cross sections of these two processes could reach a few fb with reasonable parameter values. With the yearly integrated luminosity of L=500 fb-1 expected at the ILC, one could collect hundreds up to thousands of charged Higgs events via these two processes. Therefore, our researches in this paper can help us search for charged Higgs bosons, and furthermore, to test the LRTH model.
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Dynamical Entanglement of Vibrations in Integrable Dimer and Small Molecules
ZHANG Jin-Li, LIU Jin-Ming
Communications in Theoretical Physics    2013, 60 (02): 210-216.  
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By means of the reduced-density linear entropy, we investigate the properties of dynamical entanglement of vibrations in integrable dimer and realistic small molecules which are initially in the two-mode squeezed vacuum state. It is found that the entropy of the integrable dimer is periodic for weak coupling strength c1 and small squeezing parameter r, and there exists a beat phenomenon for strong c1 and large r. Moreover, the entropy of the small molecules is quasi-periodic for small r, and the beat phenomenon occurs in the entropy evolution of the two molecules C2D2 and SO2 for large r. Our results might be used for molecular quantum computing based on vibrational states.
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Emission Spectrum Property of Modulated Atom-Field Coupling System
GAO Yun-Feng, FENG Jian, LI Yue-Ke
Communications in Theoretical Physics    2013, 60 (02): 217-221.  
Abstract426)      PDF(pc) (550KB)(712)       Save
The emission spectrum of a two-level atom interacting with a single mode radiation field in the case of periodic oscillation coupling coefficient is investigated. A general expression for the emission spectrum is derived. The numerical results for the initial field in pure number stare are calculated. It is found that the effect of the coupling coefficient modulation on the spectral structure is very obvious in the case of a low modulation frequency and larger amplitude when the initial field is vacuum, which is potentially useful for exploring a modulated light source.
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Effects of Higher-Order Relativistic Nonlinearity and Wakefield During a Moderately Intense Laser Pulse Propagation in a Plasma Channel
LIU Ming-Ping, LIU Bing-Bing, LIU San-Qiu, ZHANG Fu-Yang, LIU Jie
Communications in Theoretical Physics    2013, 60 (02): 222-226.  
Abstract467)      PDF(pc) (1320KB)(690)       Save
Using a variational approach, the propagation of a moderately intense laser pulse in a parabolic preformed plasma channel is investigated. The effects of higher-order relativistic nonlinearity (HRN) and wakefield are included. The effect of HRN serves as an additional defocusing mechanism and has the same order of magnitude in the spot size as that of the transverse wakefield (TWF). The effect of longitudinal wakefield is much larger than those of HRN and TWF for an intense laser pulse with the pulse length equaling the plasma wavelength. The catastrophic focusing of the laser spot size would be prevented in the present of HRN and then it varies with periodic focusing oscillations.
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Spherical Kadomtsev-Petviashvili Solitons in a Suprathermal Complex Plasma
Mehran Shahmansouri, Jafar Borhanian
Communications in Theoretical Physics    2013, 60 (02): 227-232.  
Abstract505)      PDF(pc) (916KB)(1197)       Save
The nonlinear aspects of nonplanar dust acoustic (DA) solitary waves are investigated in an unmagnetized complex plasma comprising of cold dust grains, kappa-distributed ions as well as electrons. The nonplanar DA solitons are studied based on the reductive perturbation technique. It is shown that the evolution of DA solitons is governed by a spherical Kadomtsev-Petviashvili (sKP) equation and then the impact of suprathermality on the spatial structure as well as the nature of DA soliton is studied. It seems that the properties of DA solitons in nonplanar geometry are quite different from that of the planar solitons.
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First-principles Study on the Magnetic, Half-metal and Thermoelectric Transport Properties of Inorganic-Organic Hybrid Compounds [C4N2H12][Fe4(HPO3)2(C2O4)3]
LI Yan-Li, ZHANG Dian-Na
Communications in Theoretical Physics    2013, 60 (02): 233-239.  
Abstract422)      PDF(pc) (2244KB)(1428)       Save
The electronic structure, magnetic and half-metal properties of inorganic-organic hybrid compound [C4N2H12][Fe4(HPO3)2(C2O4)3] are investigated by using the full-potential linearized augmented plane wave (FPLAPW) method within density-functional theory (DFT) calculations. The density of states (DOS), the total energy of the cell and the spontaneous magnetic moment of [C4N2H12][Fe4(HPO3)2(C2O4)3] are calculated. The calculation results reveal that the low-temperature phase of [C4N2H12][Fe4(HPO3)2(C2O4)3] exhibits a stable ferromagnetic (FM) ground state, and we find that this organic compound is a half-metal in FM state. In addition, we have calculated antiferromagnetically coupled interactions, revealing the existence of antiferromagnetic (AFM), which is in agreement with the experiment. We have also found that [C4N2H12][Fe4(HPO3)2(C2O4)3] is a semiconductor in the AFM state with a band gap of about 0.40 eV. Subsequently, the transport properties for potential thermoelectric applications have been studied in detail based on the Boltzmann transport theory.
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Effects of Bond Alternation on the Ground-State Phase Diagram of One-Dimensional XXZ Model
QIANG Ling, LIU Guang-Hua, TIAN Guang-Shan
Communications in Theoretical Physics    2013, 60 (02): 240-246.  
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The ground-state properties and quantum phase transitions (QPTs) of the one-dimensional bond-alternative XXZ model are investigated by the infinite time-evolving block decimation (iTEBD) method. The bond-alternative effects on its ground-state phase diagram are discussed in detail. Once the bond alternation is taken into account, the antiferromagnetic phase (Δ > 1) will be destroyed at a given critical point and change into a disordered phase without nonlocal string order. The QPT is shown to be second-order, and the whole phase diagram is provided. For the ferromagnetic phase region (Δ < -1), the critical point rc always equals 1 (independent of Δ), and the QPT for this case is shown to be first-order. The dimerized Heisenberg model is also discussed, and two disordered phases can be distinguished by with or without nonlocal string orders. Both the bipartite entanglement and the fidelity per site, as two kinds of model-independent measures, are capable of describing all the QPTs in such a quantum model.
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Reduction of Protein Networks Models by Passivity Preserving Projection
Luca Mesin, Flavio Canavero, Lamberto Rondoni
Communications in Theoretical Physics    2013, 60 (02): 247-257.  
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Reduction of complex protein networks models is of great importance. The accuracy of a passivity preserving algorithm (PRIMA) for model order reduction (MOR) is here tested on protein networks, introducing innovative variations of the standard PRIMA method to fit the problem at hand. The reduction method does not require to solve the complete system, resulting in a promising tool for studying very large-scale models for which the full solution cannot be computed. The mathematical structure of the considered kinetic equations is preserved. Keeping constant the reduction factor, the approximation error is lower for larger systems.
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Detecting Communities by Revised Max-flow Method in Networks
LIU Chuan-Jian, ZHU Zhi-Qiang, WU Jian-Liang
Communications in Theoretical Physics    2013, 60 (02): 258-262.  
Abstract464)      PDF(pc) (1242KB)(874)       Save
A ubiquitous phenomenon in networks is the presence of communities within which the network connections are dense and between which they are sparser. This paper proposes a max-flow algorithm in bipartite networks to detect communities in general networks. Firstly, we construct a bipartite network in accordance with a general network and derive a revised max-flow problem in order to uncover the community structure. Then we present a local heuristic algorithm to find the optimal solution of the revised max-flow problem. This method is applied to a variety of real-world and artificial complex networks, and the partition results confirm its effectiveness and accuracy.
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