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Phonon Polariton Dispersion in Metal-Doped Nanocomposite Superlattice System

Journal of Optical Communications 2023年第2期44卷 237-242页

作者： Krishnamurthy, R. Revathy, V. Wilson, K. S. Joseph Taya, Sofyan A. Amiri, I.S. Department of Electronics and Communication Engineering Sri Vasavi Engineering College Andhra Pradesh Tadepalligudem India Department of Physics Sethu Institute of Technology Tamilnadu Kariapatti India Karumathur Tamilnadu Madurai625 514 India Physics Department Islamic University of Gaza Gaza Palestine Computational Optics Research Group Advanced Institute of Materials Science Ton Duc Thang University Ho Chi Minh City Viet Nam Faculty of Applied Sciences Ton Duc Thang University Ho Chi Minh City Viet Nam

Copper nanoparticles (Cu) anchored lithium niobate (LiNbO3) nanostructures were prepared by a simple hydrothermal technique. The fine and sparse Cu nanoparticles were homogeneously dispersed over the surface of LiNbO3. An effectual anchoring of Cu was evidenced from the acquired reflection planes in diffraction analysis, which clearly indicate the face-centered cubic structure of Cu. The UV-Visible spectrum of LiNbO3 and Cu/LiNbO3 nanocomposites were also studied. When the Cu nanoparticles were doped with LiNbO3/LiTaO3 superlattice system, the change in the dispersion relation was observed theoretically. The characteristics of the polariton dispersion variation with filling factor of Cu nanoparticles concentration were investigated systematically. The importance of the polariton modes in communication sector was analyzed and the occurrence of new modes on the polaritonic gap, where the propagation of the electromagnetic wave is forbidden, were obtained in the system due to the presence of copper nanoparticles. © 2019 Walter de Gruyter GmbH, Berlin/Boston.

关键词： Polariton

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Molecular Opacity Calculations for Lithium Hydride at Low Temperature

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Chinese physics Letters 2020年第12期37卷 24-30页

作者： Gui-Ying Liang Yi-Geng Peng Rui Li Yong Wu Jian-Guo Wang Institute of Applied Physics and Computational Mathematics Beijing 100088China Department of Applied Physics Nanjing University of Science and TechnologyNanjing 210094China Department of Physics College of ScienceQiqihar UniversityQiqihar 161006China HEDPS Center for Applied Physics and TechnologyPeking UniversityBeijing 100084China

The opacities of the lithium hydride molecule are calculated for temperatures of 300 K,1000 K,1500 K,and 2000 K,at a pressure of 10 atm,in which the contributions from the five low-lying electronic states are *** ab initio multi-reference single and double excitation configuration interaction(MRDCI)method is applied to compute the potential energy curves(PECs)of the 7 LiH,including four 1∑+states and one 1Πstate,as well as the corresponding transition dipole moments between these *** ro-vibrational energy levels are calculated based on the PECs obtained,together with the spectroscopic *** addition,the partition functions are also computed,and are provided at temperatures ranging from 10 K to 2000 K for 7 LiH,7 LiD,6 LiH,and 6 LiD.

关键词： Lithium hydride partition

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High-pressure elastic anisotropy and superconductivity of hafnium:A first-principles calculation

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Chinese physics B 2021年第5期30卷 547-557页

作者： Cheng-Bin Zhang Wei-Dong Li Ping Zhang Bao-Tian Wang Institute of Theoretical Physics and Department of Physics and Collaborative Innovation Center of Extreme OpticsShanxi UniversityTaiyuan 030006China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Spallation Neutron Source Science Center Dongguan 523803China LCP Institute of Applied Physics and Computational MathematicsBeijing 100088China

The elastic anisotropy and superconductivity upon hydrostatic compression ofα,ω,and β Hf are investigated using first-principle *** results of elastic anisotropies show that they increase with increasing pressure for α and ω phases,while decrease upon compression forβ*** calculated superconducting transition temperatures are in excellent agreement with ***-phonon coupling constants(λ)are increasing with pressure for α and ω phases,while decreasing for β *** β phase,the large values ofλare mainly due to the obvious TA1 soft *** further compression,the TA1 soft vibrational mode will disappear gradually.

关键词： first-principles elastic anisotropy superconductivity hafnium

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Diverging entanglement of critical magnons in easy-axis antiferromagnets

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Physical Review B 2025年第9期111卷 094402-094402页

作者： Jongjun M. Lee Hyun-Woo Lee Myung-Joong Hwang Department of Physics Pohang University of Science and Technology (POSTECH) Pohang 37673 Korea Division of Natural and Applied Sciences Duke Kunshan University Kunshan Jiangsu 215300 China Zu Chongzhi Center for Mathematics and Computational Science Duke Kunshan University Kunshan Jiangsu 215300 China

We study the instability of antiferromagnets with easy-axis anisotropy under a magnetic field, uncovering single or even multiple phase transitions at the boundary between noncollinear and collinear spin orderings. Near the phase boundary, the entanglement between the sublattice magnons diverges due to the interplay among antiferromagnetic exchange interaction, anisotropy, and magnetic field. Furthermore, our study reveals that this magnetic criticality extends to a superradiant phase transition within cavity magnonics systems. The magnon-photon interaction results in diverging cavity photon numbers and squeezing in the ground state at the transition points between spin orderings. This investigation not only elucidates the criticality of multicomponent squeezed magnons in antiferromagnets, but also proposes cavity photon measurements as a viable method for detecting magnetic phase transitions.

关键词： Anisotropy

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Highly excited quantum state-selective capture dynamics in slow Ar8+−H2 collisions

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Physical Review A 2024年第3期109卷 032819-032819页

作者： Md Abul Kalam Azad Siddiki G. P. Zhao L. Liu Deepankar Misra Department of Nuclear and Atomic Physics Tata Institute of Fundamental Research Homi Bhabha Road Colaba Mumbai 400005 India College of Data Science Jiaxing University Jiaxing 314001 China Data Center for High Energy Density Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China

We report on the combined experimental and theoretical studies of the single-electron capture collisions of Ar8+ projectiles with the H2 molecules at 1, 2, and 4 keV/u collision energies. The nondissociative recoil H2+ molecular ions are measured in coincidence with the charge-changing Ar7+ projectiles. The relative cross sections of the different state-selective capture channels are obtained from the experimentally measured Q-value spectra. The 1s electron transfers to the highly excited 4d+4f, 5s, 5p, 5d+5f+5g, 6s+6p, and 6d+6f+6g+6h states are resolved experimentally. The differential scattering angle distributions for the dominant 1s to 5s, 5p, and 5d+5f+5g transitions are compared with the two-center atomic orbital close-coupling methods. A collision energy-dependent dynamical coupling effect is also observed for the 1s→5p0 and 1s→5p±1 transitions. The dominant oscillatory structures in the scattering-angle distributions are attributed to Stueckelberg-type oscillations. In contrast, the less visible undulations in the smaller scattering angles imprint the signature of the quantum matter-wave scattering of the projectiles. The quantum nature of the oscillations in the angular distributions is further validated by classical calculations. Our study thus illustrates the highly excited quantum state-selective electron capture process and sheds light on the scattering-angle-range-dependent collision dynamics for highly charged ion-molecule collisions in the highly perturbative regime.

关键词： Atomic & molecular collisions Scattering of atoms, molecules, clusters & ions Scattering theory

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Spin loop-current textures in Hubbard models

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Physical Review B 2023年第19期108卷 195118-195118页

作者： Kazuya Shinjo Shigetoshi Sota Seiji Yunoki Takami Tohyama Computational Quantum Matter Research Team RIKEN Center for Emergent Matter Science (CEMS) Wako Saitama 351-0198 Japan Computational Materials Science Research Team RIKEN Center for Computational Science (R-CCS) Kobe Hyogo 650-0047 Japan Quantum Computational Science Research Team RIKEN Center for Quantum Computing (RQC) Wako Saitama 351-0198 Japan Computational Condensed Matter Physics Laboratory RIKEN Cluster for Pioneering Research (CPR) Saitama 351-0198 Japan Department of Applied Physics Tokyo University of Science Tokyo 125-8585 Japan

The recent experimental observations of loop current in Sr2IrO4, YBa2Cu3O7, and Sr14Cu24O41 have inspired a theoretical study that broadly redefines loop current as a manifestation of quantum liquid crystals. Using the density-matrix renormalization group method, we investigate the emergence of spin loop-current (sLC) textures in carrier-doped (i) excitonic insulators, (ii) orbital-selective Mott insulators, and (iii) two-dimensional Mott insulators, modeled by a two-orbital Hubbard model on a ladder lattice in (i) and (ii) and a single-orbital Hubbard model on a square lattice in (iii). Calculating the spatial distribution of spin current around a bond to which a pinning field is applied, we find conditions for longer-ranged sLC correlations. In system (i), when using the model parameters employed to describe the excitonic condensation, we find that a sLC texture appears near half-filling, associated with an excitonic condensation in a spin channel. In system (ii), using typical sets of model parameters for BaFe2Se3, we find that a sLC texture appears at electron fillings where a block-type antiferromagnetism develops. In system (iii), introducing a next-nearest-neighbor hopping t′∼−0.25 (in units of the nearest-neighbor hopping) suggested for high-Tc cuprates, we find that an axial-sLC texture emerges at hole-carrier density δ=0.125, where the charge stripe simultaneously appears.

关键词： Spin current Stripes Cuprates Fermionic condensates Liquid crystals Multiferroics Two-dimensional electron system Density matrix renormalization group Hubbard model

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On the convergence of the pseudospectral approximation of reproduction numbers for age-structured models

arXiv

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arXiv 2024年

作者： De Reggi, Simone Scarabel, Francesca Vermiglio, Rossana CDLAb - Computational Dynamics Laboratory University of Udine Italy Department of Mathematics Computer Science and Physics University of Udine Italy Department of Applied Mathematics University of Leeds United Kingdom

We rigorously investigate the convergence of a new numerical method, recently proposed by the authors, to approximate the reproduction numbers of a large class of age-structured population models with finite age span. The method consists in reformulating the problem on a space of absolutely continuous functions via an integral mapping. For any chosen splitting into birth and transition processes, we first define an operator that maps a generation to the next one (corresponding to the Next Generation Operator in the case of R0). Then, we approximate the infinite-dimensional operator with a matrix using pseudospectral discretization. In this paper, we prove that the spectral radius of the resulting matrix converges to the true reproduction number, and the (interpolation of the) corresponding eigenvector converges to the associated eigenfunction, with convergence order that depends on the regularity of the model coefficients. Results are confirmed experimentally and applications to epidemiology are *** Codes 34L16, 47B07, 65L15, 65L60, 65N12, 92D25 © 2024, CC BY.

关键词： Eigenvalues and eigenfunctions

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Controlling inversion and time-reversal symmetries by subcycle pulses in the one-dimensional extended Hubbard model

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Physical Review B 2023年第19期107卷 195103-195103页

Owning to their high controllability, laser pulses have contributed greatly to our understanding of strongly correlated electron systems. However, typical multicycle pulses do not control the symmetry of systems, which plays an important role in the emergence of novel quantum phases. Here, we demonstrate that subcycle pulses whose oscillation is less than one period within a pulse envelope can control inversion and time-reversal symmetries in the electronic states of the one-dimensional extended Hubbard model. Using an ultrashort subcycle pulse, one can generate a steady electric current (SEC) in a photoexcited state due to an Aharonov-Bohm flux instantaneously introduced through the phase of an electric field. Consequently, time-reversal symmetry is broken. In contrast, a broad subcycle pulse does not induce SEC but instead generates electric polarization, thus breaking inversion symmetry. Both symmetry breakings in a photoexcited state can be monitored by second-harmonic generation. These findings provide a new methodology for designing the symmetries of electronic states and open up a new field of subcycle-pulse engineering.

关键词： Nonequilibrium statistical mechanics Photoinduced effect Quantum quench Ultrafast optics 1-dimensional systems Nonequilibrium lattice models Strongly correlated systems Density matrix renormalization group Extended Hubbard model Optical second-harmonic generation Ultrafast femtosecond pump probe

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Two-dimensional TiNBr as photocatalyst for overall water splitting

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Physical Review Materials 2025年第2期9卷 025802-025802页

作者： Yatong Wang Geert Brocks Ceren Tayran Süleyman Er DIFFER – Dutch Institute for Fundamental Energy Research De Zaale 20 5612 AJ Eindhoven the Netherlands Materials Simulation and Modeling Department of Applied Physics Eindhoven University of Technology 5600 MB Eindhoven the Netherlands Computational Chemical Physics Faculty of Science and Technology and MESA+ Institute for Nanotechnology University of Twente 7500 AE Enschede the Netherlands Department of Physics Faculty of Science Gazi University Ankara 06500 Turkey

Two-dimensional (2D) Janus materials have gained increasing attention as water-splitting photocatalysts for hydrogen production. We use first-principles calculations to predict a stable 2D Janus T−TiNBr structure with strong near-ultraviolet sunlight absorption and band edges that align favorably with the water redox potentials for oxygen and hydrogen evolution. We show that the optical and electronic properties of T−TiNBr can be modulated to a certain extent by applying external uniaxial strain. Explicit calculations of the redox reactions reveal that solar-driven water splitting is viable at the N-side of T−TiNBr while the Br-side requires modifications such as vacancy creation, the application of an external potential, or adjustment of the pH conditions.

关键词： Redox reactions

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Adaptive energy-preserving algorithms for guiding center system

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Plasma science and Technology 2023年第4期25卷 11-22页

作者：朱贝贝刘健张嘉炜祝爱卿唐贻发 Department of Applied Mathematics School of Mathematics and PhysicsUniversity of Science and Technology BeijingBeijing 100083Peopleʼs Republic of China School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230026Peopleʼs Republic of China Advanced algorithm Joint Lab Shandong Computer Science CenterQilu University of TechnologyJinan 250014Peopleʼs Republic of China The State Key Laboratory of Scientific and Engineering Computing The Institute of Computational Mathematics and Scientific/Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190Peopleʼs Republic of China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049Peopleʼs Republic of China

We develop two types of adaptive energy preserving algorithms based on the averaged vector field for the guiding center dynamics,which plays a key role in magnetized *** adaptive scheme is applied to the Gauss Legendre’s quadrature rules and time stepsize respectively to overcome the energy drift problem in traditional energy-preserving *** new adaptive algorithms are second order,and their algebraic order is carefully *** results show that the global energy errors are bounded to the machine precision over long time using these adaptive algorithms without massive extra computation cost.

关键词： guiding center system energy-preserving methods adaptive energy conservation

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