990 results match your criteria: "Beijing Computational Science Research Center[Affiliation]"

Artificial honeycomb lattices are essential for understanding exotic quantum phenomena arising from the interplay between Dirac physics and electron correlation. This work shows that the top two moiré valence bands in rhombohedral-stacked twisted MoS bilayers (tb-MoS) form a honeycomb lattice with massless Dirac fermions. The hopping and Coulomb interaction parameters are explicitly determined based on large-scale ab initio calculations.

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Disorder-order transition-induced unusual bandgap bowing effect of tin-lead mixed perovskites.

Sci Adv

January 2025

Department of Materials Science and Engineering, Shenzhen Key Laboratory of Full Spectral Solar Electricity Generation (FSSEG), Southern University of Science and Technology, No. 1088, Xueyuan Rd., Shenzhen 518055, Guangdong, China.

Owing to the predominant merit of tunable bandgaps, tin-lead mixed perovskites have shown great potentials in realizing near-infrared optoelectronics and are receiving increasing attention. However, despite the merit, there is still a lack of fundamental understanding of the bandgap variation as a function of Sn/Pb ratio, mainly because the films are easy to segregate in terms of both composition and phase. Here, we report a fully stoichiometric synthesis of monocrystalline FAPbSnI nanocrystals as well as their atomic-scale imaging.

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The physical process in the macroscopic world unfolds along a single time direction, while the evolution of a quantum system is reversible in principle. How to recover a quantum system to its past state is a complex issue of both fundamental and practical interests. In this article, we experimentally demonstrate a novel method for recovering the state in quantum walks (QWs), also known as full-state revival.

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Two-dimensional electronic spectroscopy (2DES) has high spectral resolution and is a useful tool for studying atomic dynamics. In this paper, we show a smallest unit of electromagnetically induced transparency (EIT) for 2DES, i.e.

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With reduced dimensionality and a high surface area-to-volume ratio, two-dimensional (2D) semiconductors exhibit intriguing electronic properties that are exceptionally sensitive to surrounding environments, including directly interfacing gate dielectrics. These influences are tightly correlated to their inherent behavior, making it critical to examine when extrinsic charge carriers are intentionally introduced to the channel for complementary functionality. This study explores the physical origin of the competitive transition between intrinsic and extrinsic charge carrier conduction in extrinsically -doped MoS, highlighting the central role of interactions of the channel with amorphous gate dielectrics.

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Length-dependent water permeation through a graphene channel.

Phys Chem Chem Phys

January 2025

MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing, and Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China.

Water confined in two-dimensional channels exhibits unique properties, such as rich morphology, specific phase transition and a low dielectric constant. In this work, molecular dynamics simulations have been used to study the water transport in two-dimensional graphene channels. The structures and dynamics of water under confinement show strong dependence on the channel length and thickness of the channels.

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Polymorphs commonly exist for various materials, enabling phase engineering for diverse material properties. While the crystal structures of different polymorphs can, in principle, be experimentally characterized, interpreting and understanding complex crystal structures can be very challenging. Using Ga_{2}O_{3} as a prototype, here we show that the crystal structure of γ-Ga_{2}O_{3} has long been misinterpreted from either theory or experiment.

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Rapid and precise forecasting of dynamical systems is critical to ensuring safe aerospace missions. Previous forecasting research has primarily concentrated on global trend analysis using full-scale inputs. However, time series arising from real-world applications such as aerospace propulsion, exhibit a distinct dynamical periodicity over a limited timeframe.

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Article Synopsis
  • - The study focuses on Type-II heterostructures made from transition-metal dichalcogenides, particularly the MoSe/WSe combination, which allows for efficient separation of electrons and holes.
  • - Researchers used density-functional theory to examine six different configurations of the heterostructure, finding that all configurations had Type-II band alignment and that applying an electric field could effectively change their band gaps.
  • - The findings suggest that while strong interlayer coupling can lead to direct to indirect band gap transitions, twist angles between 13.2° and 46.8° showed no major change in the band structure, highlighting the MoSe/WSe heterostructure's potential for optoelectronic and nanoelectronic applications.
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Oxygen Defect Site Filling Strategy Induced Moderate Enrichment of Reactants for Efficient Electrocatalytic Biomass Upgrading.

Adv Sci (Weinh)

December 2024

State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Advanced Catalytic Engineering Research Center of the Ministry of Education, Hunan University, Changsha, 410082, P. R. China.

The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) provides a feasible approach for the efficient utilization of biomass. Defect regulation is an effective strategy in the field of biomass upgrading to enhance the adsorption capacity of reactants and thus increase the activity. However, how to select appropriate strategies to regulate the over-enrichment of reactants induced by excessive oxygen vacancy is still a huge challenge.

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Charge stripes have been widely observed in many different types of unconventional superconductors, holding varying periods ( ) and intensities. However, a general understanding on the interplay between charge stripes and superconducting properties is still incomplete. Here, using large-scale unbiased numerical simulations on a general inhomogeneous Hubbard model, we discover that the charge-stripe period , which is variable in different real material systems, could dictate the pairing symmetries-d wave for and d waves for .

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Oxide-Metal Hybrid Glass Nanomembranes with Exceptional Thermal Stability.

Nano Lett

November 2024

Department of Mechanical Engineering, College of Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong 999077, China.

Contrary to oxide or polymeric glasses, metallic glasses are infamously known for their relatively limited thermal stability, which is often characterized by their narrow supercooled liquid regions. Nonetheless, we successfully fabricated metallic-glass based nanomembranes with an ultrahigh thermal ability by a polymer surface buckling enabled exfoliation technique. These nanomembranes exhibit a distinctive nanostructure with nanosized metallic-glasses encapsulated within an interconnected nanoamorphous-oxide network.

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Solvation is a crucial task in developing efficient and selective extractants for actinide elements, but an understanding and perspective of solvent effects on the extraction of uranyl are still lacking. Herein, we present investigations into solvent effects on the geometry, stability and bonding properties of five uranyl porphyrin derivative complexes (UO(L)) in four solvents relativistic quantum chemical calculations, and reveal some trends in the influence of solvent polarity on uranyl compounds. All five [L] ligands equatorially coordinate [UO] in a hexa-dentate (κ) fashion.

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Bending-induced enhanced spatial separation of dopants and long-lived conventional nanoribbon p-n junctions.

Phys Chem Chem Phys

October 2024

Department of Physics and Hebei Advanced Thin Film Laboratory, Hebei Normal University, Shijiazhuang 050024, China.

Article Synopsis
  • The study highlights the importance of spatially separating dopants to improve the lifespan of nanoribbon p-n junctions, which are typically costly to create using van der Waals heterostructures.
  • Using atomistic quantum mechanical simulations, researchers found that bending nanoribbons alters where dopants preferentially locate, depending on their atomic sizes.
  • Larger dopants tend to cluster at the outer edges on the tensile side, while smaller ones prefer the inner edges on the compressive side, allowing for better spatial separation of n-type and p-type dopants in a more cost-effective way.
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Article Synopsis
  • Silicon-based color-centers (SiCCs) are being developed as promising quantum-light sources for integration with telecom-range Silicon Photonics platforms.
  • Traditional methods for creating SiCCs face challenges in precisely controlling emitter positions due to random ion-implantation processes.
  • A new method using low-temperature epitaxial growth allows for precise positioning of SiCCs, enabling the formation of various types, including a newly identified G'-center, which shows potential for single-photon sources and improved optical properties.
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Artificial superconducting Kondo lattice in a van der Waals heterostructure.

Nat Commun

October 2024

School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China.

Article Synopsis
  • Researchers created a Kondo lattice/superconductor heterojunction by growing monolayer VSe on bulk 2H-NbSe, using molecular beam epitaxy to explore heavy fermion physics.
  • Spectroscopic measurements revealed a new charge density wave phase in VSe and a significant Kondo resonance at the Fermi level, indicating a formed Kondo lattice throughout the film.
  • The findings suggest the critical role of magnetic interstitial V atoms in forming the CDW phase, with implications for understanding heavy fermion behaviors and their interaction with superconductivity.
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Thermal resistance of energetic materials is critical due to its impact on safety and sustainability. However, developing predictive models remains challenging because of data scarcity and limited insights into quantitative structure-property relationships. In this work, a deep learning framework, named EM-thermo, was proposed to address these challenges.

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We present the implementation of the Hubbard () and Hund () corrected Density Functional Theory (DFT + + ) functionality in the Quickstep program, which is part of the CP2K suite. The tensorial and Löwdin subspace representations are implemented and compared. Full analytical DFT + + forces are implemented and benchmarked for the tensorial and Löwdin representations.

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Article Synopsis
  • Recent experiments have confirmed ferroelectricity in two-dimensional Bi monolayers, showing that atomic layer buckling leads to spontaneous lattice distortion and charged domain walls.
  • Unlike conventional ferroelectrics where domain walls are typically charge neutral, these elemental ferroelectric monolayers exhibit stable charged 180° domain walls due to strain energy dominance.
  • The study also reveals that applying small strain can switch the stability of domain walls from charged to neutral, highlighting a new mechanism for polarization and potential applications in ferroelectronics.
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Effects of Particle Migration on the Relaxation of Shock Wave Collisions.

Entropy (Basel)

August 2024

Department of Applied Physics, School of Physics and Electronics, Hunan University, Changsha 410082, China.

Article Synopsis
  • The study focuses on the non-equilibrium characteristics that emerge during the process of shock relaxation, especially when two shock waves collide, which differs from a single shock wave's behavior.
  • Using non-equilibrium molecular dynamics simulations, researchers assessed how ultra-strong shock waves interact in a classical gas and examined the link between equilibrium relaxation time and the intensity of these shocks.
  • The findings highlighted that the movement of microscopic particles during the collision significantly affects energy changes, offering new insights into the microscopic mechanics of the relaxation process.
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Diagnosing Quantum Phase Transition Order and Deconfined Criticality via Entanglement Entropy.

Phys Rev Lett

September 2024

Institute for Advanced Study in Physics and School of Physics, Zhejiang University, Hangzhou 310058, China.

We study the scaling behavior of the Rényi entanglement entropy with smooth boundaries at the putative deconfined critical point separating the Néel antiferromagnetic and valence-bond-solid states of the two-dimensional J-Q_{3} model. We observe a subleading logarithmic term with a coefficient indicating the presence of four Goldstone modes, signifying the presence of an SO(5) symmetry at the transition point, which spontaneously breaks into an O(4) symmetry in the thermodynamic limit. This result supports the conjecture that an SO(5) symmetry emerges at the transition point, but reveals the transition to be weakly first-order.

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Article Synopsis
  • The non-Hermitian skin effect shows that in certain systems, eigenstates become localized at the edges, highlighting their sensitivity to boundary conditions.
  • Researchers have experimentally observed a new phenomenon called the non-Hermitian edge burst, where there is a rapid accumulation of loss at the boundary during time evolution.
  • Utilizing photonic quantum walks, the experiment verifies this edge burst and reveals its detailed dynamics, opening up new possibilities to explore real-time behavior in non-Hermitian topological systems.
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Incognizant 1T/1H Charge-Density-Wave Phases in Monolayer NbTe.

Nano Lett

September 2024

School of Physics and Astronomy, Beijing Normal University, Beijing 100875, China.

While experimental realization of multiple charge-density waves (CDWs) has been ascribed to monolayer 1T-NbTe, their atomic structures are still largely unclear, preventing a deep understanding of their novel electronic structures. Here, comparing first-principles-calculated orbital textures with reported STM measurements, we successfully identify multiple CDWs in monolayer NbTe. Surprisingly, we reveal that both 1T/1H phases could exist in monolayer NbTe, which was incognizant before.

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Article Synopsis
  • - The successful development of group-III nitride epilayers on van der Waals (vdW) substrates, like AlN on graphene, presents new possibilities for creating high-quality semiconductor thin films while igniting discussions about their growth mechanisms.
  • - Researchers propose a new model for this process called hybrid vdW epitaxy (HVE), which is based on both computational simulations and experimental evidence.
  • - The findings show that HVE features unique interfacial interactions and a strong correlation between in-plane and out-of-plane growth, differing from traditional growth models and suggesting a novel approach to material growth.
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