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Finite-temperature phonon dispersion and vibrational dynamics of BaTiO3 from first-principles molecular dynamics

Physical Review B 2022年第1期105卷 014304-014304页

作者： Xiaohan Zhang Chunyi Zhang Cui Zhang Ping Zhang Wei Kang HEDPS Center for Applied Physics and Technology and School of Physics Peking University Beijing 100871 China HEDPS Center for Applied Physics and Technology and College of Engineering Peking University Beijing 100871 China Institute of Physics Chinese Academy of Sciences Beijing 100190 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China

A systematic investigation of the finite-temperature phonon dispersion, including its smearing and temperature effects, is carried out using autocorrelation function method together with first-principles molecular dynamics method along the [001] direction of BaTiO3, as an illustrating example of entropy-stabilized structures. A unique anharmonicity in the cubic phase mainly derived from the interactions between titanium and oxygen atoms is revealed, which provides extremely strong damping and smearing to longitudinal optical phonons but no discernible effect on the shift of phonon energies. The anharmonicity gives rise to a nearly constant density distribution in a cubic region around the equilibrium position of the relative motion of titanium atoms with respect to oxygen atoms. These results may help to gain a further insight into complex interactions in entropy-stabilized structures and provide an essential benchmark reference to the development of the promising machine-learning based molecular dynamics methods for the investigation of phonon properties.

关键词： Acoustic phonons Optical phonons Paraelectrics Single crystal materials Density functional theory Molecular dynamics

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Layer Hall counterflow as a model probe of magic-angle twisted bilayer graphene

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Physical Review B 2024年第15期109卷 155114-155114页

作者： Jihang Zhu Dawei Zhai Cong Xiao Wang Yao Condensed Matter Theory Center and Joint Quantum Institute Department of Physics University of Maryland College Park Maryland 20742 USA Max Planck Institute for the Physics of Complex Systems 01187 Dresden Germany New Cornerstone Science Laboratory Department of Physics the University of Hong Kong Hong Kong China HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong Hong Kong China Institute of Applied Physics and Materials Engineering University of Macau Taipa Macau SAR China

The recent constructions of flat moiré minibands in specifically twisted multilayer graphene and twisted transition metal dichalcogenides (TMDs) have facilitated the observation of strong correlations with convenient tunability. These correlations in flat bands result in band dispersion heavily influenced by carrier densities, leading to filling-dependent quasiparticle band renormalizations. Particularly, in magic-angle twisted bilayer graphene (MATBG), the band structure—including the quasiparticle energy and wave function—is crucial in understanding the correlated properties. Previous theoretical studies have demonstrated the presence of a time-reversal-even charge Hall counterflow in response to a direct current (DC) electric field in twisted bilayers as chiral structures. In this study, we show that such layer Hall counterflow can serve as a sensitive probe for MATBG model parameters, which are currently ambiguous as a result of unavoidable structural relaxation and twist-angle disorder. We present the layer Hall counterflow and the associated in-plane magnetization for three different MATBG continuum models, based on which many-body interacting models have been widely applied to study strong correlations in MATBG. At the single-particle level, our findings indicate notable differences in layer-projected Hall conductivity, both in magnitude and sign, between different MATBG continuum models. Furthermore, our self-consistent Hartree calculations, performed on each of these single-particle continuum models, reveal renormalized layer-projected Hall conductivity by the self-consistent Hartree field.

关键词： Electrical conductivity Electronic structure Hall effect Transport phenomena 2-dimensional systems Strongly correlated systems Twisted heterostructures Band structure methods Boltzmann theory k dot p method

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Enhancement of Proton-Boron Nuclear Reactions by Utilizing a Meshed Catcher Target

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Physical Review applied 2023年第3期20卷 034053-034053页

作者： A.D. Liu Z.Y. Liu K. Li Y.L. Yao C.T. Zhou S.P. Zhu X.T. He B. Qiao Center for Applied Physics and Technology HEDPS and SKLNPT School of Physics Peking University Beijing 100871 China Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology Center for Advanced Material Diagnostic Technology and College of Engineering Physics Shenzhen Technology University Shenzhen 518118 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China Frontiers Science Center for Nano-optoelectronic Peking University Beijing 100094 China

The proton-boron (pB) reaction has attracted extensive interest for confinement fusion since it produces energetic α particles without neutrons. Based on the pitcher-catcher geometry, a scheme to achieve a high-yielding pB nuclear reaction is proposed, where a meshed catcher target is used. The hot electrons generated by the interaction between laser and pitcher target induce a sheath field in the meshes that accelerates protons in the catcher target to drive a nuclear reaction. Not only is the number of protons increased because the action area of the sheath field becomes larger, but also the energy of protons is well controlled to meet the optimal value by adjusting the size of the mesh based on laser intensity. Two-dimensional particle-in-cell simulations show that our scheme has a 6-times improvement in the yield of nuclear reaction compared with the traditional solid catcher target. With a further increase of laser intensity, the gain of nuclear reaction yield also increases. Our approach provides an idea for the research of laser-driven pB nuclear reaction studies and compact α sources.

关键词： Fusion products High-energy-density plasmas Laser driven ion acceleration Nuclear fusion Nucleon induced nuclear reactions Target design & fabrication Protons Particle-in-cell methods

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Effect of leading-edge and trailing-edge camber morphing on gust load for an elastic wing

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Chinese Journal of Aeronautics 2025年第4期 208-224页

作者： Yuting DAI Yating HU You WU Chen SONG Chao YANG School of Aeronautic Science and Engineering Beihang University Tianmushan Laboratory CAEP Software Center for High-Performance Numerical Simulation Institute of Applied Physics and Computational Mathematics

This paper investigates the influence of the spanwise-distributed trailing-edge camber morphing on the dynamic stall characteristics of a finite-span wing at Re=2×10～*** mathematical model of the spanwise-distributed trailing-edge camber morphing is established based on Chebyshev polynomials,and the deformed wing surface is modeled by a spline surface according to the rib's morphing in the chordwise *** computational Fluid Dynamics(CFD)method is adopted to obtain flow-field results and aerodynamic *** SST-γ model is introduced and the overset mesh technique is *** numerical results show that the spanwisedistributed trailing-edge morphing obviously changes the aerodynamic and energy transfer characteristics of the dynamic *** when the phase difference between the trailing-edge motion and the wing pitch is-π/2,the interaction between the three-dimensional(3-D) Leading-Edge Vortex(LEV) and Trailing-Edge Vortex(TEV) is strengthened,and the work done by the aerodynamic force turns *** indicates that the trailing-edge deformation has the potential to suppress the oscillation amplitude of stall *** also found that as the trailing-edge camber morphing varies more complexly along the spanwise direction,the suppression effect decreases accordingly.

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Photodissociation dynamics of SiH+: Rovibrationally resolved Feshbach resonances mediated by coupled excited states in the ultraviolet region

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Physical Review A 2025年第1期111卷 013118-013118页

作者： Yu Kun Yang Xing Guang Su Kun Wang Yongjun Cheng Quan Wei Nan Zeqing Wang Danny L. Yeager Yong Wu Jian Guo Wang School of Physics Henan Normal University Xinxiang 453000 China Institute of Environmental Science Shanxi University Taiyuan 030006 China School of Physics and Information Technology Shaanxi Normal University Xi'an 710119 China Department of Physics Renmin University of China Beijing 100872 China Department of Chemistry Texas A&M University College Station Texas 77843 USA Institute of Applied Physics and Computational Mathematics P.O. Box 8009 Beijing 100088 China

Photodissociation cross sections of SiH+ have been explored within the uncoupled theoretical framework, notably in the work of Stancil et al. [Astrophys. J. 486, 574 (1997)]. However, in the SiH+ system, there are significant nonadiabatic interactions between the 31Π and 41Π states, which substantially affect the photodissociation process, particularly in the region between the Lyman α line and the Lyman limit. These nonadiabatic couplings give rise to numerous Feshbach resonances, significantly altering the final photodissociation cross sections. The present study highlights the critical importance of incorporating nonadiabatic electronic couplings to achieve accurate cross-section calculations. The results substantially enrich the data set on small molecular structures and spectra in interstellar clouds, providing essential theoretical support for future experimental investigations and for the modeling and analysis of stellar spectra. Additionally, this work offers key insights into the underlying physical mechanisms by which Feshbach resonances modulate line shapes in coupled photodissociation scattering cross sections.

关键词： Photodissociation

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Monolayer Fe3GaX2 (X=I, Br, Sb): high-temperature two-dimensional magnets and a novel partially ordered spin state

arXiv

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arXiv 2024年

作者： Wang, Qiuhao Yang, Xinlong Zheng, Fawei Zhang, Ping School of Physics and Physical Engineering Qufu Normal University Qufu273165 China School of Physics Beijing Institute of Technology Beijing100081 China Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing100081 China Institute of Applied Physics and Computational Mathematics Beijing100088 China

We systematically investigated the effects of charge doping and strain on monolayer Fe3GaTe2, and proposed three new novel two-dimensional magnetic materials: monolayer Fe3GaX2 (X=I, Br, Sb). We found that both strain and charge doping can tune the magnetic interactions, and the tuning by charge doping is more significant. Differential charge analysis revealed that the doped charges predominantly accumulate around Te atoms. Based on this insight, we introduced Fe3GaI2, Fe3GaBr2, and Fe3GaSb2 monolayers. The Fe3GaI2 and Fe3GaBr2 monolayers contain I and Br atoms rather than Te atoms, emulate electron-doped Fe3GaTe2 monolayer, resulting in notably high Tc values of 867 K and 844 K, respectively. In contrast, the Fe3GaSb2 monolayer mimics hole-doped Fe3GaTe2 monolayer, presents a mix of FM and antiferromagnetic interactions, manifesting a distinctive partially ordered magnetic state. Our study demonstrates that substitution atoms based on the charge-doping effect offer a promising approach for predicting new magnetic materials. The proposed Fe3GaI2, Fe3GaBr2, and Fe3GaSb2 monolayers hold great potential for spintronics applications, and may stimulate the pursuit of new types of spin liquid. Copyright © 2024, The Authors. All rights reserved.

关键词： Monolayers

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Chirality-selective transparency induced by lattice resonance in bilayer metasurfaces

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Photonics Research 2021年第4期9卷 484-493页

作者： Shuxia Zhao Lei Shao Jianfang Wang Hai-Qing Lin Wei Zhang Institute of Applied Physics and Computational Mathematics Beijing 100088China Beijing Computational Science Research Center Beijing 100193China Department of Physics The Chinese University of Hong KongShatinHong Kong SARChina

Chiral optical responses of bilayer metasurfaces made of twisted metallic nanorods are investigated in detail with focus on the collective effect due to lattice resonance(LR).Using an analytical approach based on the coupled dipole method(supported by full wave simulation),we find optical chirality is dramatically increased by the coupling between localized surface plasmon resonances and *** collective effect results in significant chiral signal even for metasurfaces made of achiral unit *** interlayer coupling generally destroys the Wood’s anomaly and the associated *** making use of Pancharatnam–Berry(PB)phase and propagation phase,one can modulate the optical activity effectively and achieve chirality-selective transparency induced by LR in a designed structure with a g-factor of absorption as high as 1.99(close to the upper limit of 2).Our studies not only reveal a new mechanism of modulating chiral optical response by combination effects from PB phase,propagation phase,and LR,but also give a quantitative relationship between the geometry configuration and chiral optical properties,thus providing helpful guidance for device design.

关键词： transparency chiral lattice

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Can microplastic contamination affect the wing morphology and wingbeat frequency of Aedes aegypti (Diptera: Culicidae) mosquitoes?

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Environmental Science and Pollution Research 2024年第49期31卷 59289-59301页

作者： de Nadai, Barbara Lepretti Moura, Lidia Castro, Gleyson B. Silva, Kamila Jessie Sammarro Maletzke, André Gustavo Corbi, Juliano José Batista, Gustavo E. A. P. A. Machado, Renato Bobsin Computational Entomology Laboratory Department of Engineering and Exact Sciences Western Paraná State University Foz Do Iguaçu Brazil Environmental Engineering and Sanitation Leonardo da Vinci University Center Indaial Brazil Laboratory of Ecotoxicology and Applied Ecology Department of Hydraulic Engineering and Sanitation São Carlos School of Engineering University of Sao Paulo Sao Carlos Brazil Environmental Biophotonics Laboratory São Carlos Institute of Physics University of Sao Paulo Sao Carlos Brazil School of Computer Science and Engineering University of New South Wales Sydney Australia

Microplastics (MPs) are increasingly widespread in the environment, which raises questions about their potential effects at different biological levels. It is essential to assess the impacts on biodiversity, and it is also crucial to understand whether the presence of MPs can interfere with the biological traits of species of relevance in public health. Considering that the life-history traits of mosquitoes, such as size and the wingbeat frequency (WBF), are related to its vector competence, here, we study the effects of 106 particles L−1 (as expected concentration of MPs on the environment, using the polyethylene type) on WBF, as well as wing morphology, testing the Culicidae species found across all continents, Aedes aegypti, as an indicator. Results show that larvae survival and development were not affected by the tested concentration of MP. Geometric morphometrics showed some asymmetry in female mosquito wings, which were also smaller for individuals reared in MP suspension. As for WBF, results did not indicate any significant differences between females. Male mosquitoes, however, showed alterations in WBF and wing morphology, suggesting possible sex-specific reactions to microplastic exposure. Also, the combination of morphological parameters analyzed as covariates (wing centroid size and body weight) did not significantly affect WBF for both female and male mosquitoes. Overall, this study shows an inaugural investigation of the effects of MP on wing size and WBF on Ae. aegypti, shedding light on these parameters tested for a current pollution issue and its impact on a virus vector. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.

关键词： Invertebrates

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Growth of Sobolev norms for 2D cubic nonlinear Schrödinger equation with partial harmonic potential

arXiv

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arXiv 2023年

作者： Deng, Mingming Su, Xiaoyan Zheng, Jiqiang Graduate School of China Academy of Engineering Physics Beijing100088 China School of Mathematics Sciences Beijing Normal University Beijing100875 China Institute of Applied Physics and Computational Mathematics Beijing100088 China

In this paper, we study the 2D cubic nonlinear Schrödinger equation (NLS) with the partial harmonic potential. First, we prove the local well-posedness in Bourgain spaces by establishing a key bilinear estimate associated with the partial harmonic oscillator. Then, we give the polynomial bound of the Sobolev norms for the solutions using the method of the Planchon, Tzvetkov, and Visciglia in [11].MSC Codes 35A01, 35B40, 35Q55 © 2023, CC BY.

关键词： Polynomials

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Fisher zeroes and dynamical quantum phase transitions for two- and three-dimensional models

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Physical Review B 2024年第22期110卷 224302-224302页

作者： Tomasz Masłowski Hadi Cheraghi Jesko Sirker Nicholas Sedlmayr The Faculty of Mathematics and Applied Physics Rzeszów University of Technology al. Powstańców Warszawy 6 35-959 Rzeszów Poland Computational Physics Laboratory Physics Unit Faculty of Engineering and Natural Sciences Tampere University Tampere FI-33014 Finland Helsinki Institute of Physics University of Helsinki FI-00014 Finland Department of Physics and Astronomy and Manitoba Quantum Institute University of Manitoba Winnipeg Canada R3T 2N2 Institute of Physics M. Curie-Skłodowska University 20-031 Lublin Poland

Dynamical quantum phase transitions are nonanalyticities in a dynamical free energy (or return rate), which occur at critical times. Although extensively studied in one dimension, the exact nature of the nonanalyticity in two and three dimensions has not yet been fully investigated. In two dimensions, results so far are known only for relatively simple two-band models. Here, we study the general two- and three-dimensional cases. We establish the relation between the nonanalyticities in different dimensions, and the functional form of the densities of Fisher zeros. We show, in particular, that entering a critical region where the density of Fisher zeros is nonzero at the boundary always leads to a cusp in the derivative of the return rate while the return rate itself is smooth. We illustrate our results by obtaining analytical results for exemplary two- and three-dimensional models.

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