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arXiv 2023年

作者： Zhang, Duo Liu, Xinzijian Zhang, Xiangyu Zhang, Chengqian Cai, Chun Bi, Hangrui Du, Yiming Qin, Xuejian Peng, Anyang Huang, Jiameng Li, Bowen Shan, Yifan Zeng, Jinzhe Zhang, Yuzhi Liu, Siyuan Li, Yifan Chang, Junhan Wang, Xinyan Zhou, Shuo Liu, Jianchuan Luo, Xiaoshan Wang, Zhenyu Jiang, Wanrun Wu, Jing Yang, Yudi Yang, Jiyuan Yang, Manyi Gong, Fu-Qiang Zhang, Linshuang Shi, Mengchao Dai, Fu-Zhi York, Darrin M. Liu, Shi Zhu, Tong Zhong, Zhicheng Lv, Jian Cheng, Jun Jia, Weile Chen, Mohan Ke, Guolin Weinan, E. Zhang, Linfeng Wang, Han AI for Science Institute Beijing100080 China DP Technology Beijing100080 China Academy for Advanced Interdisciplinary Studies Peking University Beijing100871 China State Key Lab of Processors Institute of Computing Technology Chinese Academy of Sciences Beijing100871 China University of Chinese Academy of Sciences Beijing100871 China HEDPS CAPT College of Engineering Peking University Beijing100871 China Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo315201 China CAS Key Laboratory of Magnetic Materials and Devices Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology Chinese Academy of Sciences Ningbo315201 China School of Electronics Engineering and Computer Science Peking University Beijing100871 China Shanghai Engineering Research Center of Molecular Therapeutics & New Drug Development School of Chemistry and Molecular Engineering East China Normal University Shanghai200062 China Laboratory for Biomolecular Simulation Research Institute for Quantitative Biomedicine Department of Chemistry and Chemical Biology Rutgers University PiscatawayNJ08854 United States Department of Chemistry Princeton University PrincetonNJ08540 United States College of Chemistry and Molecular Engineering Peking University Beijing100871 China Yuanpei College Peking University Beijing100871 China School of Electrical Engineering and Electronic Information Xihua University Chengdu610039 China State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun130012 China Key Laboratory of Material Simulation Methods & Software of Ministry of Education College of Physics Jilin University Changchun130012 China International Center of Future Science Jilin University Changchun130012 China Key Laboratory for Quantum Materials of Zhejiang Province Department of Physics School of Science Westlake University Zhejiang Hangzhou310030 China Atomistic Simulations Italia

The rapid advancements in artificial intelligence (AI) are catalyzing transformative changes in atomic modeling, simulation, and design. AI-driven potential energy models have demonstrated the capability to conduct large-scale, long-duration simulations with the accuracy of ab initio electronic structure methods. However, the model generation process remains a bottleneck for large-scale applications. We propose a shift towards a model-centric ecosystem, wherein a large atomic model (LAM), pre-trained across multiple disciplines, can be efficiently fine-tuned and distilled for various downstream tasks, thereby establishing a new framework for molecular modeling. In this study, we introduce the DPA-2 architecture as a prototype for LAMs. Pre-trained on a diverse array of chemical and materials systems using a multi-task approach, DPA-2 demonstrates superior generalization capabilities across multiple downstream tasks compared to the traditional single-task pre-training and fine-tuning methodologies. Our approach sets the stage for the development and broad application of LAMs in molecular and materials simulation research. Copyright © 2023, The Authors. All rights reserved.

关键词： Multi-task learning

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A Novel Method for Solving Time-Dependent 2D Advection-Diffusion-Reaction Equations to Model Transfer in Nonlinear Anisotropic Media

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Communications in Computational Physics 2019年第6期26卷 233-264页

作者： Ji Lin Sergiy Reutskiy C.S.Chen Jun Lu State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering International Center for Simulation Software in Engineering and SciencesCollege of Mechanics and MaterialsHohai UniversityNanjing 211100China State Institution"Institute of Technical Problems of Magnetism of the National Academy of Sciences of Ukraine" Industrialnaya St.1961106KharkovUkraine Department of Mathematics University of Southern MississippiHattiesburgMS 39406USA Nanjing Hydraulic Research Institute Nanjing 210029China State Key Laboratory of Hydrology Water Resources and Hydraulic Engineering Nanjing 210098China

This paper presents a new numerical technique for solving initial and bound-ary value problems with unsteady strongly nonlinear advection diffusion reaction(ADR)*** method is based on the use of the radial basis functions(RBF)for the approximation space of the *** Crank-Nicolson scheme is used for approximation in *** results in a sequence of stationary nonlinear ADR *** equations are solved sequentially at each time step using the proposed semi-analytical technique based on the *** approximate solution is sought in the form of the analytical expansion over basis functions and contains free *** basis functions are constructed in such a way that the expansion satisfies the boundary conditions of the problem for any choice of the free *** free parameters are determined by substitution of the expansion in the equation and collocation in the solution *** the case of a nonlinear equation,we use the well-known procedure of *** transforms the original equation into a sequence of the linear ones on each time *** numerical examples confirm the high accuracy and robustness of the proposed numerical scheme.

关键词： Advection diffusion reaction time-dependent fully nonlinear anisotropic media Crank-Nicolson scheme meshless method

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What makes an explosion happen?

arXiv

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arXiv 2020年

作者： Sun, Chang Qing Yao, Chuang Zhang, Lei Huang, Yongli EBEAM School of Materials Science and Engineering Yangtze Normal University Chongqing408100 China NOVITAS School of Electrical and Electronic Engineering Nanyang Technological University 639798 Singapore Software Center for High Performance Numerical Simulation Institute of Applied Physics and Computational Mathematics Beijing100088 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing100088 China School of Materials Science and Engineering Xiangtan University Xiangtan411105 China

Energy density and structure stability are of key concerns in devising energy materials such as CNHO molecular crystals and the emerging cyclo-N5- complexes for desired explosive functionalities with a mechanism being open for exploration. An extension of the recent progress in solvation suggests that a combination of the intermolecular hydrogen bond (X:H–Y or HB with ‘:’ being electron lone pair of X, Y = O or N) tension and the super-HB (X:⇔:Y) or anti-HB (H⇔H) compression not only stabilizes the structure but also stores excessive energy by shortening the intramolecular bonds. The presence of the X:H constrains and the presence of the X:⇔:Y and/or H⇔H fosters the explosion. Observations suggest that the absence of X:H–Y tension results in the spontaneous aquatic explosion of alkali metals and molten alkali halides. The lack of X:⇔:Y repulsion fosters no explosion of the molten NaCl in liquid NH3, nor the molten Na2CO3 salt or H3BO3 acid in water. The findings shall offer guidelines for devising efficient energy materials and reconciling the nature origin of water ice, aqueous solutions, and explosive energy materials – significance of electron lone pairs and protons. Copyright © 2020, The Authors. All rights reserved.

关键词： Explosions

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Effect of anharmonicity on the hcp to bcc transition in beryllium at high-pressure and high-temperature conditions

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Physical Review B 2019年第6期99卷 064102-064102页

作者： Jia-Wei Xian Jun Yan Hai-Feng Liu Tao Sun Gong-Mu Zhang Xing-Yu Gao Hai-Feng Song Institute of Applied Physics and Computational Mathematics Beijing 100094 China Key Laboratory of Computational Geodynamics University of Chinese Academy of Sciences Beijing 100049 China CAEP Software Center for High Performance Numerical Simulation Beijing 100088 China

We investigate the hcp to bcc phase transition in beryllium (Be) at high-pressure and -temperature (PT) conditions. A recently developed hybrid approach that combines first-principles molecular dynamics and lattice dynamics is used to account for anharmonic contributions to the free energy. Anharmonic effects are shown to be strong at high T in both hcp and bcc Be. They are stronger in hcp Be than in bcc Be, as evidenced by the larger anharmonic vibrational entropy of hcp Be. We find that anharmonicity has a significant influence on the hcp to bcc transition at high-PT conditions. It substantially enlarges the stability domain of hcp Be at high T compared with that calculated under the quasiharmonic approximation (QHA), as a result bringing theoretical predictions into good consistency with recent experimental observations. After considering anharmonic effects, the calculated pressure and temperature of the hcp/bcc/liquid triple point increase from about 85 to 165 GPa, and from about 3300 to 4200 K, respectively, and the predicted Clapeyron slope at the triple point takes a value of −7.4±0.7K/GPa, noticeably larger in magnitude than previous QHA results in the range of −3 to 2 K/GPa.

关键词： Entropy Phonons Solid-solid transformations Structural phase transition Alkaline earth metals First-principles calculations Molecular dynamics

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Enhanced polarization switching characteristics of HfO2 ultrathin films via acceptor-donor co-doping

arXiv

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arXiv 2024年

作者： Zhou, Chao Ma, Liyang Feng, Yanpeng Kuo, Chang-Yang Ku, Yu-Chieh Liu, Cheng-En Cheng, Xianlong Li, Jingxuan Si, Yangyang Huang, Haoliang Huang, Yan Zhao, Hongjian Chang, Chun-Fu Das, Sujit Liu, Shi Chen, Zuhuang School of Materials Science and Engineering Harbin Institute of Technology Shenzhen518055 China Fudan University Shanghai200433 China Key Laboratory for Quantum Materials of Zhejiang Province Department of Physics School of Science Westlake University Zhejiang Hangzhou310024 China Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Wenhua Road 72 Shenyang110016 China Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu30010 Taiwan Department of Physics Southern University of Science and Technology Shenzhen518055 China Key Laboratory of Material Simulation Methods and Software Ministry of Education College of Physics Jilin University Changchun130012 China Max-Planck Institute for Chemical Physics of Solids Nöthnitzer Str. 40 Dresden01187 Germany Materials Research Centre Indian Institute of Science Bangalore560012 India Flexible Printed Electronics Technology Center Harbin Institute of Technology Shenzhen518055 China

In the realm of ferroelectric memories, HfO2-based ferroelectrics stand out because of their exceptional CMOS compatibility and scalability. Nevertheless, their switchable polarization and switching speed are not on par with those of perovskite ferroelectrics. It is widely acknowledged that defects play a crucial role in stabilizing the metastable polar phase of HfO2. Simultaneously, defects also pin the domain walls and impede the switching process, ultimately rendering the sluggish switching of HfO2. Herein, we present an effective strategy involving acceptor-donor co-doping to effectively tackle this dilemma. Remarkably enhanced ferroelectricity and the fastest switching process ever reported among HfO2 polar devices are observed in La3+-Ta5+ co-doped HfO2 ultrathin films. Moreover, robust macro-electrical characteristics of co-doped films persist even at a thickness as low as 3 nm, expanding potential applications of HfO2 in ultrathin devices. Our systematic investigations further demonstrate that synergistic effects of uniform microstructure and smaller switching barrier introduced by co-doping ensure the enhanced ferroelectricity and shortened switching time. The co-doping strategy offers an effective avenue to control the defect state and improve the ferroelectric properties of HfO2 films. Emerging demands for high-speed computing and high-density memory render the Von Neumann architecture less competent for future challenges. To address these issues, neuromorphic devices that mimic human synapses behaviors1,2 along with in-memory computing technologies3,4, have garnered significant attention. Ferroelectric memory devices, with stable memory state, low energy consumption, fast switching speed, and reliable endurance, emerge as promising candidates for these evolving technologies. Nevertheless, hindered by the size effect5 and incompatibility with standard complementary metal oxide semiconductor (CMOS) processing, the development of ferroelectric memory device

关键词： Ferroelectricity

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A first principles study of high pressure phase diagram of bismuth at 0 ~14 GPa based on structure search and quasi-harmonic approximation

arXiv

引用

arXiv 2019年

作者： Zhao, Ya-Fan Li, Shou-Rui Gao, Xing-Yu Tian, Ming-Feng Song, Hai-Feng Institute of Applied Physics and Computational Mathematics Beijing100088 China Software Center for High Performance Numerical Simulation China Academy of Engineering Physics Beijing100088 China Institute of Fluid Physics China Academy of Engineering Physics Mianyang621900 China

We have performed first principles study for bismuth crystal structure at pressure from 0~14 GPa based on structure search and quasi-harmonic approximation. A new stable phase with Pbcm symmetry is predicted by structure search method. We find that the most stable structures of bismuth at 0 K are R3_m(0 ~ 3.29 GPa), Pbcm (3.29 GPa ~ 4.91 GPa), Cmce (4.91 GPa ~ 10.57 GPa) and Im3_m (> 10.57 GPa), respectively. By quasi-harmonic approximation, we predicted the phase diagram of bismuth from first principles calculations. We found that the phase transition pressure reduces with increasing temperature. Our calculation agrees with the trend of experimental phase diagram. The P4/ncc model structure for the incommensurate Bi-III phase is not a stable phase in our calculation. A better model for the Bi-III phase is still needed. We also note that the spin-orbital interaction is very important for phase-diagram simulation of bismuth. By using first principle based structure search method, we successfully determine the low temperature high pressure phase diagram of bismuth, showing that the structure search method can effectively find the most stable structure of given material at high pressure even with high Z elements. Copyright © 2019, The Authors. All rights reserved.

关键词： Crystal structure

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Valence transition in topological Kondo insulator

arXiv

引用

arXiv 2019年

作者： Zhuang, Jia-Tao Zheng, Xiao-Jun Wang, Zhi-Yong Ming, Xing Li, Huan Liu, Yu Song, Hai-Feng College of Science Guilin University of Technology Guilin541004 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Software Center for High Performance Numerical Simulation China Academy of Engineering Physics Beijing100088 China

We investigate the valence transition in three-dimensional topological Kondo insulator through slave-boson analysis of periodic Anderson model. By including the effect of intra-atomic Coulomb correlation Ufc between conduction and local electrons, we find a first-order valence transition from Kondo region to mixed valence upon ascending of local level above a critical Ufc, and this valence transition usually occurs very close to or simultaneously with a topological transition. Near the parameter region of zero-temperature valence transition, rise of temperature can generate a thermal valence transition from mixed valence to Kondo region, accompanied by a first-order topological transition. Remarkably, above a critical Ufc which is considerable smaller than that generating paramagnetic valence transition, the original continuous antiferromagnetic transition is shifted to first order one, at which a discontinuous valence shift takes place. Upon increased Ufc, the paramagnetic valence transition approaches then converges with the first-order antiferromagnetic transition, leaving an significant valence shift on the magnetic boundary. The continuous antiferromagnetic transition, first-order antiferromagnetic transition, paramagnetic valence transition and topological transitions are all summarized in a global phase diagram. Our proposed exotic transition processes can help to understand the thermal valence variation as well as the valence shift around the pressure-induced magnetic transition in topological Kondo insulator candidates and in other heavy-fermion systems. Copyright © 2019, The Authors. All rights reserved.

关键词： Paramagnetism

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lMFF: Efficient and Scalable layered Materials Force Field on Heterogeneous Many-Core Processors

lMFF: Efficient and Scalable layered Materials Force Field o...

引用

Supercomputing Conference

作者： Ping Gao Xiaohui Duan Jiaxu Guo Jin Wang Zhenya Song Lizhen Cui Xiangxu Meng Xin Liu Wusheng Zhang Ming Ma Guohui Li Dexun Chen Haohuan Fu Wei Xue Weiguo Liu Guangwen Yang School of Software Shandong University Jinan China National Supercomputing Center in Wuxi Wuxi China Department of Computer Science and Technology Tsinghua University Beijing China College of Computer Science and Technology Jilin University Changchun China Department of Engineering Mechanics Center for Nano and Micro Mechanics Tsinghua University Beijing China Ministry of Natural Resources First Institute of Oceanography and Key Laboratory of Marine Science and Numerical Modeling Qingdao China Joint SDU-NTU Centre for Artificial Intelligence Research (C-FAIR) Jinan China Engineering Research Center of Digital Media Technology Ministry of Education Jinan China Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian China Department of Earth System Science Ministry of Education Key Lab for Earth System Modeling Tsinghua University Beijing China

ISBN: (数字)9781450384421

ISBN: (纸本)9781665483902

LAMMPS is one of the most popular Molecular Dynamic (MD) packages and is widely used in the field of physics, chemistry and materials simulation. Layered Materials Force Field (LMFF) is our expansion of the LAMMPS potential function based on the Tersoff potential and inter-layer potential (ILP) in LAMMPS. LMFF is designed to study layered materials such as graphene and boron hexanitride. It is universal and does not depend on any platform. We have also carried out a series of optimizations on LMFF and the optimization work is carried out on the new generation of Sunway supercomputer, called SWLMFF. Experiments show that our implementation is efficient, scalable and portable. When generic LMFF is ported to Intel Xeon Gold 6278C, $2\times$ performance improvement is achieved. For the optimized SWLMFF, the overall performance improvement is nearly $200-330\times$ compared to the original ILP and Tersoff potentials. And SWLMFF has good parallel efficiency of 95%-100% under weak scaling with 2.7 million atoms on a single process. The maximum atomic system simulated by SWLMFF is close to $2^{31}$ atoms. And nanosecond simulations in one day can be realized.

关键词： Program processors Atomic layer deposition High performance computing Force Graphene Supercomputers Optimization

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Magnetic and topological transitions in three-dimensional topological Kondo insulator

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Chinese Physics Letters 2018年第12期35卷 59-63页

作者：黎欢王志勇郑晓军刘瑜钟寅 College of Science Guilin University of Technology Institute of Applied Physics and Computational Mathematics Software Center for High Performance Numerical Simulation China Academy of Engineering Physics Center for Interdisciplinary Studies & Key Laboratory for Magnetism and Magnetic Materials of the MoE Lanzhou University

Using an extended slave-boson method,we draw a global phase diagram summarizing both magnetic phases and paramagnetic（PM） topological insulators（TIs） in a three-dimensional topological Kondo insulator（TKI）. By including electron hopping（EH） up to the third neighbors, we identify four strong TI（STI） phases and two weak TI（WTI） phases. Then, the PM phase diagrams characterizing topological transitions between these TIs are depicted as functions of EH,f-electron energy level,and hybridization constant. We also find an insulator-metal transition from an STI phase that has surface Fermi rings and spin textures in qualitative agreement with the TKI candidate SmBs. In the weak hybridization regime, antiferromagnetic（AF） order naturally arises in the phase diagrams. Depending on how the magnetic boundary crosses the PM topological transition lines,AF phases are classified into the AF topological insulator（AFTI） and the non-topological AF insulator, according to their Z2 indices. In two small regions of parameter space, two distinct topological transition processes between AF phases occur, leading to two types of AFTIs showing distinguishable surface dispersions around their Dirac points.

关键词： STI WTI TKI

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Spin-Triplet Excitonic Insulator: The Case of Semihydrogenated Graphene

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Physical Review Letters 2020年第16期124卷 166401-166401页

作者： Zeyu Jiang Wenkai Lou Yu Liu Yuanchang Li Haifeng Song Kai Chang Wenhui Duan Shengbai Zhang State Key Laboratory of Low-Dimensional Quantum Physics and Collaborative Innovation Center of Quantum Matter Department of Physics Tsinghua University Beijing 100084 China SKLSM Institute of Semiconductors Chinese Academy of Sciences P.O. Box 912 Beijing 100083 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China Key Lab of advanced optoelectronic quantum architecture and measurement (MOE) and Advanced Research Institute of Multidisciplinary Science Beijing Institute of Technology Beijing 100081 China CAEP Software Center for High Performance Numerical Simulation Beijing 100088 China Beijing Academy of Quantum Information Sciences Beijing 100193 China Institute for Advanced Study Tsinghua University Beijing 100084 China Department of Physics Applied Physics and Astronomy Rensselaer Polytechnic Institute Troy New York 12180 USA

While various excitonic insulators have been studied in the literature, due to the perceived too-small spin splitting, spin-triplet excitonic insulator is rare. In two-dimensional systems such as a semihydrogenated graphene (known as graphone), however, it is possible, as revealed by first-principles calculations coupled with Bethe-Salpeter equation. The critical temperature, given by an effective Hamiltonian, is 11.5 K. While detecting excitonic insulators is still a daunting challenge, the condensation of triplet excitons will result in spin superfluidity, which can be directly measured by a transport experiment. Nonlocal dielectric screening also leads to an unexpected phenomenon, namely, an indirect-to-direct transition crossover between single-particle band and exciton dispersion in the semihydrogenated graphene, which offers yet another test by experiment.

关键词： Excitons Graphene First-principles calculations

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