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Ideal Quadratic Nodal Point with Large Surface Arc States in Half-Heusler Material Scbipt

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SSRN 2022年

作者： Yang, Tie Liu, Ying Tan, Xingwen Zhang, Xiaoming Wu, Zhimin Zhang, Gang State Key Lab for Reliability and Intelligence of Electrical Equipment China School of Physical Science and Technology Southwest University Chongqing400715 China School of Physics and Electronic Engineering Chongqing Normal University Chongqing401331 China School of Materials Science and Engineering Hebei University of Technology Tianjin300130 China Institute of High Performance Computing Agency for Science Technology and Research Connexis 138632 Singapore

Recently, the research focus of topological states in electronic systems has been shifted from the conventional linear type to high order dispersion, in which more exotic physical properties are exhibited, such as high topological charge, large magnetoresponse and unusual transport behavior. In this work, based on first principles calculations, we proposed a quadratic nodal point semimetal, the half-Heusler material ScBiPt. Detailed band structures reveal that an ideal nodal point is present exactly at the Fermi level and, more importantly, it exhibits quadratic dispersion along all directions, which has also been confirmed from the symmetry analyzation and effective model analysis. Moreover, when the spin orbital coupling effect is considered, the nodal point changes from triple to quadruple degeneracy but the quadratic dispersion is still maintained. Two prominent arc surface states are emanated from the nodal point and they are well separated from the bulk band, making the future experimental verification extremely beneficial. Overall, the current quadratic nodal point material with multiple advantages can serve as an ideal platform and the relative studies can be immediately inspired and advanced. © 2022, The Authors. All rights reserved.

关键词： Topology

Suppressing Optical Loss at the Air/Glass Surface of Solar Cells Via Designing Geometric Arrays

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SSRN 2022年

作者： Shen, Xiangqian Wang, Zhiye Wangyang, Peihua Wang, Chen Zhou, Hua Xinjiang Key Laboratory of Solid State Physics and Devices School of Physical Science and Technology Xinjiang University Urumqi830046 China Sany Group China Guangxi Key Laboratory of Precision Navigation Technology and Application Guilin University of Electronic Technology Guilin541004 China School of Physics Shandong University 27 Shanda Nanlu Shandong Jinan250100 China

Optical loss at the surfaces of the solar cells is inevitable due to the refractive index difference between the air and glass and the inadequate absorption of active layer. To address this challenge, micron-sized geometry arrays such as hemisphere and hemisphere pit were prepared on quartz glass via an indirect patterning technology of UV-LIGA. By delicately controlling the size and morphology of these geometries, the average transmission (haze) of quartz glass increased from 90.51% (4.01%) to 93.91% (~75%), ensuring a greater number of incident photons to propagate into cell devices and have a prolonged optical path. As a result, an apparent reduction in optical loss at air/glass surface is observed for monocrystalline silicon solar cells coated with such a geometric array. This improvement yielded a high photocurrent of 39.87 mAcm^2 and demonstrated an ~7.2% enhancement in power conversion efficiency comparing with the flat one. Further numerical simulation verified that the multiple rebounds in geometry structures, as well as diffraction scattering and total internal reflection are responsible for this light harvesting. © 2022, The Authors. All rights reserved.

关键词： Geometry

Diagnosing Quantum Phases Using Long-Range Two-Site Quantum Resource Behaviors

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arXiv

arXiv 2023年

作者： Su, Lin-Lin Ren, Jun Ma, Wen-Long Wang, Z.D. Bai, Yan-Kui College of Physics Hebei Key Laboratory of Photophysics Research and Application Hebei Normal University Hebei Shijiazhuang050024 China State Key Laboratory of Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences Beijing100083 China Department of Physics HK Institute of Quantum Science & Technology Guangdong-Hong Kong Joint Laboratory of Quantum Matter The University of Hong Kong Pokfulam Road Hong Kong Center of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Beijing100049 China

We propose and demonstrate that the behaviors of long-range, two-site quantum resources can effectively diagnose quantum phases. In an XX spin chain with symmetry-breaking quantum phase transitions, we reveal that the asymptotic and oscillating decay modes of quantum coherence or quantum discord, along with two-site distance, can identify two spin-liquid phases. Furthermore, based on our analytical results of spin correlation functions, we confirm the existence of long-range entanglement in the system and establish a connection between two-site entanglement and quantum phases. Additionally, for the extended Ising model with topological phase transitions, we find that coherence and quantum discord behaviors can also signify topological quantum phases. In particular, we discover the quantum resource freezing phenomenon, where topologically protected long-range quantum resources may have potential applications in quantum information processing. © 2023, CC BY.

关键词： Ising model

First-Principles Study on the Stability and Degradation of the Lead-Free Double Perovskite Materials Cs2b'Bicl6 (B' = Li, Na, K) Under Natural Environment

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SSRN 2023年

作者： Ming, Xing Liu, Yunhui Ma, Yiping Gong, Xujia Xiao, Feng College of Physics and Electronic Information Engineering Key Laboratory of Low-dimensional Structural Physics and Application Education Department of Guangxi Zhuang Autonomous Region Guilin University of Technology Guilin541004 China Engineering Research Center of Environment-Friendly Functional Materials Ministry of Education Fujian Key Laboratory of Photoelectric Functional Materials College of Materials Science & Engineering Huaqiao University Xiamen361021 China MOE Key Laboratory of New Processing Technology for Nonferrous Metal and Materials Guilin University of Technology Guilin541004 China

The stability of perovskite solar cell materials in the natural environment is crucial to their commercial application. Understanding the detailed interaction mechanism between the air or water (H2O) molecules with perovskite materials is a key way to explore their stabilities. In this study, we evaluate the geometric stabilities and thermodynamic stabilities of lead-free double perovskite materials Cs2B'BiCl6 (B' = Li, Na, K), and further explore the effect of air and H2O molecules on the stability and degradation of Cs2B'BiCl6. The calculated results indicate that the pristine Cs2B'BiCl6 materials possess good geometric stabilities and thermodynamic stabilities. Under natural environment, the N2, O2, and CO2 gas molecules hardly attack Cs2LiBiCl6 and Cs2NaBiCl6 because of positive insertion energies, while N2 and O2 can easily insert Cs2KBiCl6 due to negative insertion energies. In contrast, with respect to other gas molecules, the H2O molecules can easily insert into the lattice of all Cs2B'BiCl6 materials with negative insertion energies. Furthermore, the insertion of H2O molecules causes structural deformations of the double perovskites and resultant rotation or rupture of some octahedra. Further simulations of H2O molecules adsorption on the surface of the double perovskites reveal that the adsorption energies of H2O molecules at all adsorption sites are negative, indicating that Cs2B'BiCl6 materials are prone to absorb H2O molecules in a humid environment. Therefore, the H2O molecules are the main factor affecting the stability and degradation of all Cs2B'BiCl6. Additionally, Cs2KBiCl6 shows much worse stability, which is responsible for the scarcely experimental reports on its synthesis and characterization. © 2023, The Authors. All rights reserved.

关键词： Chlorine compounds

NMR Spectra Denoising with Vandermonde Constraints

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arXiv

arXiv 2023年

作者： Guo, Di Xu, Runmin Wu, Jinyu Lin, Meijin Du, Xiaofeng Qu, Xiaobo School of Computer and Information Engineering Fujian Engineering Research Center for Medical Data Mining and Application Xiamen University of Technology Xiamen361024 China Department of Electronic Science Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance Xiamen University Xiamen361102 China Department of Applied Marine Physics and Engineering Xiamen University Xiamen361102 China

Nuclear magnetic resonance (NMR) spectroscopy serves as an important tool to analyze chemicals and proteins in bioengineering. However, NMR signals are easily contaminated by noise during the data acquisition, which can affect subsequent quantitative analysis. Therefore, denoising NMR signals has been a long-time concern. In this work, we propose an optimization model-based iterative denoising method, CHORD-V, by treating the time-domain NMR signal as damped exponentials and maintaining the exponential signal form with a Vandermonde factorization. Results on both synthetic and realistic NMR data show that CHORD-V has a superior denoising performance over typical Cadzow and rQRd methods, and the state-of-the-art CHORD method. CHORD-V restores low-intensity spectral peaks more accurately, especially when the noise is relatively high. © 2023, CC BY.

关键词： Nuclear magnetic resonance spectroscopy

The Mechanism of Alkyl Chain Modulation the Efficiency of Y-Series Non-Fullerene Acceptor: A Dft Approach

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SSRN 2024年

作者： Zhang, Zhengli Ding, Zhao Sun, Chenghua Guo, Xiang Yang, Chen Wang, Yi Hu, Mi Yang, Ting Liu, Xuefei Li, Junli College of Big Data and Information Engineering Guizhou University Huaxi Road Huaxi District Guizhou Guiyang China Engineering Research Center of Semiconductor Power Device Reliability Ministry of Education Huaxi Road Huaxi District Guizhou Guiyang China School of Physics and Electronic Science Guizhou Normal University Huaxi University Town Guizhou Guiyang China Department of Chemistry and Biotechnology Swinburne University of Technology HawthornVIC Australia

Y6, a highly efficient non-fullerene acceptor, could present distinctly different power conversion efficiency in organic solar cells When coordinated with variant alkyl chains. However, the underlying mechanism is still unclear. To dissect this point, ten kinds of Y-series acceptors with variant side chains are studied. The density functional theory is used to calculate their ground geometry, frontier molecular orbital, ultraviolet-visible absorption spectra the free energy of solvation, intramolecular electron transfer, and electronic structures on the excited state in chloroform. Results reveal that the presence of the branched R1 could reduce the dihedral angle and balance the planarity of molecular skeletons. The free energy of solvation is less than -1.5 eV and R2 has a greater impact on it than R1. Acceptors with longer R2 have better light absorption between 400nm and 600nm. Molecules that possess branched R1 and longer R2 are found to be promising candidates for highly efficient acceptors. © 2024, The Authors. All rights reserved.

关键词： Density functional theory

DPA-2:a large atomic model as a multitask learner

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npj Computational Materials 2024年第1期10卷 185-199页

作者： Duo Zhang Xinzijian Liu Xiangyu Zhang Chengqian Zhang Chun Cai Hangrui Bi Yiming Du Xuejian Qin Anyang Peng Jiameng Huang Bowen Li Yifan Shan Jinzhe Zeng Yuzhi Zhang Siyuan Liu Yifan Li Junhan Chang Xinyan Wang Shuo Zhou Jianchuan Liu Xiaoshan Luo Zhenyu Wang Wanrun Jiang Jing Wu Yudi Yang Jiyuan Yang Manyi Yang Fu-Qiang Gong Linshuang Zhang Mengchao Shi Fu-Zhi Dai Darrin M.York Shi Liu Tong Zhu Zhicheng Zhong Jian Lv Jun Cheng Weile Jia Mohan Chen Guolin Ke Weinan E Linfeng Zhang Han Wang AI for Science Institute BeijingP.R.China DP Technology BeijingP.R.China Academy for Advanced Interdisciplinary Studies Peking UniversityBeijingP.R.China State Key Lab of Processors Institute of Computing TechnologyChinese Academy of SciencesBeijingP.R.China University of Chinese Academy of Sciences BeijingP.R.China HEDPS CAPTCollege of EngineeringPeking UniversityBeijingP.R.China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingboP.R.China CAS Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology Chinese Academy of SciencesNingboP.R.China School of Electronics Engineering and Computer Science Peking UniversityBeijingP.R.China Shanghai Engineering Research Center of Molecular Therapeutics&New Drug Development School of Chemistry and Molecular EngineeringEast China Normal UniversityShanghaiP.R.China Laboratory for Biomolecular Simulation Research Institute for Quantitative Biomedicine and Department of Chemistry and Chemical BiologyRutgers UniversityPiscatawayNJUSA Department of Chemistry Princeton UniversityPrincetonNJUSA College of Chemistry and Molecular Engineering Peking UniversityBeijingP.R.China Yuanpei College Peking UniversityBeijingP.R.China School of Electrical Engineering and Electronic Information Xihua UniversityChengduP.R.China State Key Laboratory of Superhard Materials College of PhysicsJilin UniversityChangchunP.R.China Key Laboratory of Material Simulation Methods&Software of Ministry of Education College of PhysicsJilin UniversityChangchunP.R.China International Center of Future Science Jilin UniversityChangchunP.R.China Key Laboratory for Quantum Materialsof Zhejiang Province Department of PhysicsSchool of ScienceWestlake UniversityHangzhouP.R.China Atomistic Simulations Italian Institute of TechnologyGenovaItaly State Key Laboratory of Physical Chemistry of Solid Surface iChEMCollege of Chemistry and Chemical EngineeringXiame

The rapid advancements in artificial intelligence(AI)are catalyzing transformative changes in atomic modeling,simulation,and ***-driven potential energy models havedemonstrated the capability to conduct large-scale,long-duration simulations with the accuracy of ab initio electronic structure ***,the model generation process remains a bottleneck for large-scale *** propose a shift towards a model-centric ecosystem,wherein a large atomic model(LAM),pretrained across multiple disciplines,can be efficiently fine-tuned and distilled for various downstream tasks,thereby establishing a new framework for molecular *** this study,we introduce the DPA-2 architecture as a prototype for ***-trained on a diverse array of chemical and materials systemsusing a multi-task approach,DPA-2demonstrates superior generalization capabilities across multiple downstream tasks compared to the traditional single-task pre-training and fine-tuning *** approach sets the stage for the development and broad application of LAMs in molecular and materials simulation research.

关键词： DPA establishing thereby

An R-SIFT Image Matching Intelligent Algorithm Applied to Hardware Trojan Detection

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An R-SIFT Image Matching Intelligent Algorithm Applied to Ha...

作者： Chen Sun Pujiang Liang Lingling Li Jingjing Ma Licheng Jiao Fang Liu Science and Technology on Reliability Physics and Application of Electronic Component Laboratory Key Laboratory of Intelligent Perception and Image Understanding of Ministry of Education International Research Center for Intelligent Perception and ComputationJoint International Research Laboratory of Intelligent Perception and ComputationSchool of Artificial IntelligenceXidian University

Malicious modification, deletion or addition of some modules in the integrated circuits(ICs) will cause the chip to be attacked, which is called Hardware Trojans(HTs). Reverse engineering(RE) is a classic destructive method and widely used in HTs detection. However, RE is very time-consuming and error prone. In this paper, based on RE, we propose the R-SIFT algorithm to match image and reformulate the Trojan detection problem as change detection problem. For the R-SIFT algorithm, the ratio of exponentially weighted averages(Roewa) operator is introduced into the scale-invariant feature transform(SIFT) algorithm. Experiments show that the proposed method has 7 to 56 times more matching points than the original SIFT can be effectively applied to HTs detection.

关键词： Trojan detection R-SIFT Image matching

Benchmarking calculations of wavelengths and transition rates with spectroscopic accuracy for W xlviii through W lvi tungsten ions

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Physical Review A 2022年第2期105卷 022817-022817页

作者： Chun Yu Zhang Jin Qing Li Kai Wang Ran Si Michel Godefroid Per Jönsson Jun Xiao Ming Feng Gu Chong Yang Chen Shanghai EBIT Lab Key Laboratory of Nuclear Physics and Ion-Beam Application Institute of Modern Physics Department of Nuclear Science and Technology Fudan University Shanghai 200433 People's Republic of China Hebei Key Lab of Optic-Electronic Information and Materials The College of Physics Science and Technology Hebei University Baoding 071002 People's Republic of China Spectroscopy Quantum Chemistry and Atmospheric Remote Sensing (SQUARES) CP160/09 Université Libre de Bruxelles 1050 Brussels Belgium Department of Materials Science and Applied Mathematics Malmö University SE-20506 Malmö Sweden Space Science Laboratory University of California Berkeley California 94720 USA

Atomic properties of n=3 levels for W47+−W55+ ions (Z=74) are systematically calculated using two different and independent methods, namely, the second-order many-body perturbation theory and the multiconfiguration Dirac-Hartree-Fock method combined with the relativistic configuration interaction approach. Wavelengths and transition rates for electric- and magnetic-dipole transitions involving the n=3 levels of W47+−W55+ are calculated. In addition, we discuss in detail the importance of the valence and core-valence electron correlations, the Breit interaction, the higher-order frequency-dependent retardation correction, and the leading quantum electrodynamical corrections for transition wavelengths. Spectroscopic accuracy is achieved for the present calculated wavelengths, and most of them agree with experimental values within 0.05%. Our calculated wavelengths, combined with collisional radiative model simulations, are used to identify the yet unidentified 25 observed lines in the extremely complex spectrum between 27Å and 34Å measured by Lennartsson etal. [Phys. Rev. A 87, 062505 (2013)]. We provide additional data for 472 strong electric-dipole transitions in the wavelength range of 17–50 Å, and 185 strong magnetic-dipole transitions between 36Å and 4384Å, with a line intensity greater than 1photon/s. These can provide benchmark data for future experiments and theoretical calculations.

关键词： Atomic & molecular structure Atomic spectra