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Dynamical thermalization of Frenkel-Kontorova model in the thermodynamic limit

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Physical Review E 2016年第2期93卷 022216-022216页

作者： Zhenjun Zhang Chunmei Tang Peiqing Tong College of Science Hohai University Nanjing Jiangsu 210098 People's Republic of China School of Physics Science and Technology Nanjing Normal University Nanjing Jiangsu 210023 People's Republic of China Jiangsu Provincial Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing Jiangsu 210023 People's Republic of China

We study numerically the process of dynamical thermalization in the Frenkel-Kontorova (FK) model with weak nonlinearity. The total energy has initially equidistributed among some of the lowest frequency linear modes. It is found that the energy transfers continuously to the high-frequency modes and finally evolves towards energy equipartition in the FK model. However, the metastable state, which was found in Fermi-Pasta-Ulam (FPU) model and φ4 model in a relatively short time scale, is not found in the FK model. We further perform a very accurate systematic study of the equipartition time Teq as functions of the particle number N, the nonlinear parameter β, and the energy density ɛ. In the thermodynamic limit, the dependence of Teq on β and ɛ is found to display a power law behavior: Teq∝βaɛb. The exponents a and b are numerically found to be approximately −2.0 and 1.43. This scaling law is also quite different from those of the FPU-β model and φ4 model.

关键词： Lattice dynamics Lattice models in statistical physics Lattice models in condensed matter

Topological properties and localization transition in a one-dimensional non-Hermitian lattice with a slowly varying potential

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Physical Review B 2022年第10期105卷 104201-104201页

作者： Siqing Li Mengyao Li Yi Gao Peiqing Tong Center for Quantum Transport and Thermal Energy Science Jiangsu Key Laboratory on Opto-Electronic Technology School of Physics and Technology Nanjing Normal University Nanjing 210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems School of Physics and Technology Nanjing Normal University Nanjing 210023 China

We explore the eigenenergy distribution, localization transition, and topological property of a one-dimensional non-Hermitian lattice with a slowly varying potential, which does not possess parity-time (PT) symmetry. We found that, in contrast to PT-symmetric systems whose eigenenergies can stay real until the PT-symmetry breaking point, the eigenenergies in the present system are fully complex and their distribution in the complex plane depends on the parameters. As non-Hermiticity is introduced into the system, also depending on the parameters, the eigenstates may show a crossover behavior from fully extended to fully localized as non-Hermiticity is increased, or there will be a sharp localization transition at finite non-Hermiticity. Nevertheless, this non-Hermitian system is proven to be topologically trivial, thus we conclude that in general non-Hermitian systems, the localization transition is not always of a topological nature.

关键词： Anderson localization Topological phase transition Non-Hermitean systems PT-symmetry

Heat conduction in one-dimensional aperiodic quantum Ising chains

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Physical Review E 2011年第3期83卷 031128-031128页

作者： Wenjuan Li Peiqing Tong Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing 210046 People’s Republic of China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210046 People’s Republic of China

The heat conductivity of nonperiodic quantum Ising chains whose ends are connected with heat baths at different temperatures are studied numerically by solving the Lindblad master equation. The chains are subjected to a uniform transverse field h, while the exchange coupling Jm between the nearest-neighbor spins takes the two values JA and JB arranged in Fibonacci, generalized Fibonacci, Thue-Morse, and period-doubling sequences. We calculate the energy-density profile and energy current of the resulting nonequilibrium steady states to study the heat-conducting behavior of finite but large systems. Although these nonperiodic quantum Ising chains are integrable, it is clearly found that energy gradients exist in all chains and the energy currents appear to scale as the system size 〈Q〉~Nα. By increasing the ratio of couplings, the exponent α can be modulated from α>−1 to α<−1 corresponding to the nontrivial transition from the abnormal heat transport to the heat insulator. The influences of the temperature gradient and the magnetic field to heat conduction have also been discussed.

关键词： HEAT conduction ISING model EQUATIONS FIBONACCI sequence THERMAL conductivity

Reanalysis of the most strange dibaryon within constituent quark models

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arXiv 2019年

作者： Huang, Hongxia Zhu, Xinmei Ping, Jialun Department of Physics Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China Department of Physics Yangzhou University Yangzhou225009 China

The most strange dibaryon ΩΩ with quantum numbers S = −6, I = 0, and JP = 0+, 1−, 2+, 3− is reanalyzed in the framework of quark delocalization color screening model (QDCSM) and chiral quark model (ChQM). The ΩΩ dibaryon with JP = 0+ is bound, and the one with other quantum numbers JP = 1−, 2+, 3− are all unbound in our calculation. The low-energy scattering phase shifts, the scattering length, and the effective range of the ΩΩ dibaryon with JP = 0+ also support the existence of such strange dibaryon. This dibaryon is showed to be a shallow bound state in QDCSM, while the binding energy becomes much larger in the ChQM by including the effect of the hidden-color channel coupling. And the scalar nonet meson-exchange in the ChQM also provides more attraction for the ΩΩ system. Experimental search for such most strange dibaryon will provide much information for understanding the hadron-hadron interactions in different quark models. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum theory

Is d∗(2380) a compact hexaquark state?

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arXiv 2023年

作者： Pan, Manying Zhu, Xinmei Ping, Jialun Department of Physics Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China Department of Physics Yangzhou University Yangzhou225009 China

The most fascinating dibaryon in the non-strange quark sector is d∗(2380), which was reported by WASA-at-COSY Collaboration and confirmed by A2@MAMI Collaboration. The reported mass and decay width are M ≈ 2.37 GeV, Γ ≈ 70 MeV and the quantum numbers are IJP = 03+. The structure of d∗(2380) is still in controversy. In the present calculation, the powerful method in few-body system, Gaussian Expansion Method (GEM) is employed to explore the structure of d∗(2380) in the framework of constituent quark models without assuming the presupposed structure. The results show that the radius of d∗(2380) is around 0.8 fm, it is a very compact object. Because of the compact structure, the color singlet-singlet component has a large overlap with the color octet-octet one, two colorless, large overlapped ∆s dominate the state is possible. Copyright © 2023, The Authors. All rights reserved.

关键词： Color

A novel class of energy-preserving Runge-Kutta methods for the Korteweg-de Vries equation

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arXiv 2021年

作者： Chen, Yue Gong, Yuezheng Hong, Qi Wang, Chunwu Department of Mathematics Nanjing University of Aeronautics and Astronautics Nanjing211106 China MIIT Nanjing211106 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing210023 China

In this paper, we present a quadratic auxiliary variable approach to develop a new class of energy-preserving Runge-Kutta methods for the Korteweg-de Vries equation. The quadratic auxiliary variable approach is first proposed to reformulate the original model into an equivalent system, which transforms the energy conservation law of the Korteweg-de Vries equation into two quadratic invariants of the reformulated system. Then the symplectic Runge-Kutta methods are directly employed for the reformulated model to arrive at a new kind of time semi-discrete schemes for the original problem. Under the consistent initial condition, the proposed methods are rigorously proved to maintain the original energy conservation law of the Korteweg-de Vries equation. In addition, the Fourier pseudo-spectral method is used for spatial discretization, resulting in fully discrete energy-preserving schemes. To implement the proposed methods effectively, we present a very efficient iterative technique, which not only greatly saves the calculation cost, but also achieves the purpose of practically preserving structure. Ample numerical results are addressed to confirm the expected order of accuracy, conservative property and efficiency of the proposed algorithms. Copyright © 2021, The Authors. All rights reserved.

关键词： Runge Kutta methods

Reanalysis of the most strange dibaryon within constituent quark models

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Physical Review C 2020年第3期101卷 034004-034004页

作者： Hongxia Huang Xinmei Zhu Jialun Ping Department of Physics and Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 People's Republic of China Department of Physics Yangzhou University Yangzhou 225009 People's Republic of China

The most strange dibaryon ΩΩ with quantum numbers S=−6, I=0, and JP=0+,1−,2+,3− is reanalyzed in the framework of a quark delocalization color screening model (QDCSM) and chiral quark model (ChQM). The ΩΩ dibaryon with JP=0+ is bound, and the one with other quantum numbers JP=1−,2+,3− are all unbound in our calculation. The low-energy scattering phase shifts, the scattering length, and the effective range of the ΩΩ dibaryon with JP=0+ also support the existence of such strange dibaryon. This dibaryon is showed to be a shallow bound state in QDCSM, while the binding energy becomes much larger in the ChQM by including the effect of the hidden color channels coupling. And the scalar nonet meson exchange in the ChQM also provides more attraction for the ΩΩ system. Experimental search for such most strange dibaryon will provide much information for understanding the hadron-hadron interactions in different quark models.

关键词： Nucleon-nucleon interactions Quark model

Further study of the NΩ dibaryon within constituent quark models

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Physical Review C 2015年第6期92卷 065202-065202页

作者： Hongxia Huang Jialun Ping Fan Wang Department of Physics and Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 People's Republic of China Department of Physics Nanjing University Nanjing 210093 People's Republic of China

Inspired by the discovery of the dibaryon d* and the experimental search of NΩ dibaryon with the STAR data, we study the strange dibaryon NΩ further in the framework of the quark delocalization color screening model and the chiral quark model. We have shown NΩ is a narrow resonance in ΛΞ D-wave scattering before. However, the Λ−Ξ scattering data analysis is quite complicated. Here we calculate the low-energy NΩ scattering phase shifts, scattering length, effective range, and binding energy to provide another approach of STAR data analysis. Our results show there exists an NΩ “bound” state, which can be observed by the N−Ω correlation analysis with RHIC and LHC data, or by the new developed automatic scanning system at J-PARC. In addition, we also find that the hidden-color channel coupling is important for the NΩ system to develop intermediate-range attraction.

关键词： DIBARYON QUARK models PHASE shift (Nuclear physics) QUANTUM chromodynamics QUARK-gluon plasma

Influences of weak disorder on dynamical quantum phase transitions of anisotropic XY chain

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arXiv 2019年

作者： Cao, Kaiyuan Li, Wenwen Zhong, Ming Tong, Peiqing Department of Physics Institute of Theoretical Physics Nanjing Normal University Nanjing210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China

In this paper, the effects of disorder on the dynamical quantum phase transitions (DQPTs) in the transverse-field anisotropic XY chain are studied by numerically calculating the Loschmidt echo after quench. We obtain the formula for calculating the Loschmidt echo of the inhomogeneous system in real space. By comparing the results with that of the homogeneous chain, we find that when the quench crosses the Ising transition, the small disorder will cause a new critical point. As the disorder increases, more critical points of the DQPTs will occur, constituting a critical region. In the quench across the anisotropic transition, the disorder will cause a critical region near the critical point, and the width of the critical region increases by the disordered strength. In the case of quench passing through two critical lines, the small disorder leads to the system to have three additional critical points. When the quench is in the ferromagnetic phase, the large disorder causes the two critical points of the homogeneous case to become a critical region. And for the quench in the paramagnetic phase, the DQPTs will disappear for large disorder. Copyright © 2019, The Authors. All rights reserved.

关键词： Phase transitions