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MAGUS: machine learning and graph theory assisted universal structure searcher

National Science Review 2023年第7期10卷 213-233页

作者： Junjie Wang Hao Gao Yu Han Chi Ding Shuning Pan Yong Wang Qiuhan Jia Hui-Tian Wang Dingyu Xing Jian Sun National Laboratory of Solid State Microstructures School of Physics and Collaborative Innovation Center of Advanced Microstructures Nanjing University

Crystal structure predictions based on first-principles calculations have gained great success in materials science and solid state physics.However,the remaining challenges still limit their applications in systems with a large number of atoms,especially the complexity of conformational space and the cost of local optimizations for big systems.Here,we introduce a crystal structure prediction method,MAGUS,based on the evolutionary algorithm,which addresses the above challenges with machine learning and graph theory.Techniques used in the program are summarized in detail and benchmark tests are provided.With intensive tests,we demonstrate that on-the-fly machine-learning potentials can be used to significantly reduce the number of expensive first-principles calculations,and the crystal decomposition based on graph theory can efficiently decrease the required configurations in order to find the target structures.We also summarized the representative applications of this method on several research topics,including unexpected compounds in the interior of planets and their exotic states at high pressure and high temperature(superionic,plastic,partially diffusive state,etc.);new functional materials(superhard,high-energy-density,superconducting,photoelectric materials),etc.These successful applications demonstrated that MAGUS code can help to accelerate the discovery of interesting materials and phenomena,as well as the significant value of crystal structure predictions in general.

关键词： crystal structure searching materials design ab-initio calculations density functional theory high-pressure phase transition

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Unveiling structural features and mechanical properties of amorphous Si_(2)BC_(3)N by density functional theory

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Journal of Materials Science & Technology 2023年第8期139卷 103-112页

作者： Yuchen Liu Yu Zhou Dechang Jia Zhihua Yang Daxin Li Bin Liu Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150080China School of Materials Science and Engineering Shanghai UniversityShanghai 200444China Zhejiang Laboratory Hangzhou 311100China

The atomic structural features and the mechanical properties of the Si_(2)BC_(3)N are investigated employ-ing ab-initio calculations.The chemical bonding types and their proportion are clarified.The tetrahedral and trigonal configurations,together with their nesting,are identified,which contribute to the flexibil-ity of structural characteristics.The Si-related coordination aggravates the inhomogeneous distribution of chemical bonding and weakens the tetrahedral units.The accompanying polyhedral distortion is quanti-tatively reflected by the bond length and its deviation of polyhedron units.The elastic moduli and the ideal strengths of Si_(2)BC_(3)N are found to be lower than SiC and Si_(3)N_(4),as a result of the weakening effect of coordination Si on tetrahedral units and the existence of easily distorted trigona.The balance between tetrahedral and trigonal features through composition tailor is believed an effective way for the design of Si-B-C-N ceramics for structural applications.

关键词： Amorphous SiBCN ab-initio calculations Atomic structure Electronic structure Mechanical properties

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Structural and optoelectronic properties of CsLnZnTe_(3)(Ln=La,Pr,Nd and Sm)

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Journal of Rare Earths 2023年第3期41卷 388-396,I0003页

作者： Imad Khan Ihsan Ullah Izaz Ul Haq Akbar Ali A.Dahshan Zahid Ali Iftikhar Ahmad Center for Computational Materials Science Department of PhysicsUniversity of MalakandChakdaraPakistan Department of Physics Faculty of ScienceKing Khalid UniversityP.O.Box 9004AbhaSaudi Arabia Department of Physics Faculty of SciencePort Said UniversityPort SaidEgypt Gomal University Dera Ismail KhanPakistan

Zinc telluride is a versatile wide band gap semiconductor used in many applications.But it has certain limitations like large dimensions and large band gaps.Introducing alkali metal to its bulk lattice(3D)can reduce its dimensions and lanthanide can produce a red shift in the energy gap by converting it into quaternary compounds.The alkali and lanthanide incorporated quaternary zinc tellurides CsLnZnTe_(3)(Ln=La,Pr,Nd and Sm)form layered crystal structure in which_(∞)^(2)[LnZnTe_(3)]-layers are separated by Cs+layer.The famous lanthanide contraction is experimental both from lattice constants and bond lengths.The calculated band gaps are 2.26,2.28,2.12,2.05 eV for CsLaZnTe_(3),CsPrZnTe_(3),CsNdZnTe_(3) and CsSmZnTe_(3),respectively.These compounds show direct band gap nature.The energy band gaps of these compounds have not been evaluated yet both experimentally and theoretically.Energy loss functions,refractive index and dielectric functions were also calculated to explore the potential applications of CsLnZnTe_(3) in optoelectronic devices.

关键词： Chalcogenides Optical materials Electronic structure Dimensions reduction ab-initio calculations Rare earths

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Oxidation of norbornadiene:Theoretical investigation on H-atom abstraction and related radical decomposition reactions

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Propulsion and Power Research 2023年第1期12卷 104-113页

作者： Jintao Chen Mingxia Liu Yuxiang Zhu Kairu Jin Zhenyu Tian Lijun Yang Chong-Wen Zhou School of Energy and Power Engineering Beihang UniversityBeijing 100191China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China School of Astronautics Beihang UniversityBeijing 100191China Combustion Chemistry Centre School of Biological and Chemical SciencesUniversity of GalwayGalway H91TK33Ireland

The chemical kinetics of hydrogen atom(H-atom)abstraction reactions from norbornadiene(NBD)by five radicals(H,O(^(3)P),OH,CH_(3),and HO_(2)),and the unimolecular reactions of three NBD derived radicals,were studied through high-level ab-initio calculations.The geometries optimization and vibrational frequencies calculation for all the reactants,transition states,and products were obtained at the M06-2X/6-311ttG(d,p)level of theory.The zeropoint energy(ZPE)corrected potential energy surfaces(PESs)were determined at the QCISD(T)/cc-pVDZ,TZ level of theory with basis set corrections from MP2/cc-pVDZ,TZ,QZ methods for single point energy calculations.Conventional transition state theory(TST)was used for the rate constants calculations of H-atom abstraction reactions by five radicals(H,O(^(3)P),OH,CH_(3),and HO_(2))at temperatures from 298.15 to 2000 K,while the a-site H-atom abstraction reaction rate constant of NBD by OH radical has been obtained through variational transition state theory(VTST).The results show that the H-atom abstraction reactions from the α-carbon atom of NBD are the most critical channels at low temperatures.Total rate constants for H-atom abstraction reactions by OH radical are also the fastest among all of the reaction channels investigated at the temperature range from 298.15 to 2000 K.Rice-Ramsperger-Kassel-Marcus/Master Equation(RRKM/ME)has been used to calculate the pressure-and temperature-dependent rate constants for the unimolecular reactions of three related C7H7 product radicals which generated from H-atom abstraction reaction within temperature ranges of 300-2000 K and pressures of 0.01-100 atm.A combination of composite methods has been used to calculate the temperature-dependent thermochemical properties of NBD and related radicals.All the calculated kinetics and thermochemistry data can be utilized in the model development for NBD oxidation.

关键词： Norbornadiene ab-initio calculations Rate constants Kinetic Thermochemistry

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Dominant ferromagnetic coupling over antiferromagnetic in Ni doped ZnO： First-principles calculations

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Frontiers of physics 2016年第1期11卷 121-127页

作者： Bakhtiar UI Haq Rashid Ahmed Galila abdellatif Amiruddin Shaari Faheem K. Butt Mohammed Benali Kanoun Souraya Goumri-Said Department of Physics Faculty of Science UniversitiTeknologi Malaysia UTM Skudai Johor81310 Malaysia Department of Physics Sungkyunkwan University Suwon 44 0-746 Korea Physik-Department ECS Technische Universitat Miinchen James-Franck-Straβe 1 85748 Garching Germany Department of Physics The University of Lahore 1-KM Defence Road Lahore Pakistan Department of Physics Faculty of Science Cairo University Giza Egypt physics Department College of Science AlFaisal University P.O. Box 50927 Riyadh 11533 Saudi Arabia

The low magnetic moment （MM） in diluted magnetic semiconductors （DMS） at low impurity doping levels has triggered considerable research into condensed magnetic semiconductors （CMS）.This work reports an ab-initio investigation of the electronic structures and magnetic properties of ZnO in a zinc-blende （ZB） structure doped with nickel ions. Ni-doped ZnO-based DMS and CMS exhibit a dominance of ferromagnetic coupling over antiferromagnetic. A robust increase in the magnetization has been observed as a function of Ni impurity levels. This material favors short-range magnetic interactions at the ground state, suggesting that the observed ferromagnetism is defined by the double exchange mechanism. The spin-polarized density of states （DOS） of Ni-doped ZnO characterizes it as half-metallic with a considerable energy gap for up-spin components and as metallic for-down spins. Half metallic Ni：ZnO based magnetic semiconductors with high magnetization are expected to have potential applications in spintronics.

关键词： ZnO diluted magnetic semiconductors ab-initio calculations electronic structure,magnetic properties

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The stabilities, electronic structures and elastic properties of Rb-As systems

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Chinese Physics B 2012年第4期21卷 442-450页

作者： Havva Bogaz Ozisik Kemal Colakoglu Engin Deligoz Haci Ozisik Gazi University Science Faculty Physics Department 06500 Teknikokullar AnkaraTurkey Aksaray University Faculty of Arts and Science Physics Department 68100 Campus Aksaray Turkey Gazi University Science Faculty Physics Department 06500 Teknikokullar Ankara Turkey

The structural, electronic and elastic properties of Rb As systems （RbAs in NaP, LiAs and AuCu structures, RbAs2 in the MgCu2 structure, Rb3As in NaaAs, Cu3P and Li3Bi structures, and Rb5As4 in the A5B4 structure） are investigated with the generalized gradient approximation in tile frame of density functional theory. The lattice parameters, cohesive energies, formation energies, bulk moduli and the first derivatives of the bulk moduli （to fit Murnaghan＇s equation of state） of the considered structures are calculated and reasonable agreement is obtained. In addition, the phase transition pressures are also predicted. The electronic band structures, the partial densities of states corresponding to the band structures and the charge density distributions are presented and analysed. The second-order elastic constants based on the stress-strain method and other related quantities such as Young＇s modulus, the shear modulus, Poisson＇s ratio, sound velocities, the Debye temperature and shear anisotropy factors are also estimated.

关键词： ab-initio calculations structural properties electronic properties elastic properties Rb As compounds

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Structures and phase transitions of ScH_3 under high pressure

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Chinese Physics B 2013年第5期22卷 429-433页

作者：孔博周筑文陈德良令狐荣锋 School of Physics & Electronic Sciences Guizhou Normal College College of Physical Science and Technology Sichuan University

The structures and the phase transitions of ScH3 under high pressure are investigated using first-principles calcula- tions. The calculated structural parameters at zero pressure agree well with the available experimental data. With increasing pressure, the transition sequence hcp （GdHa-type）→ C2/m →fcc→4hcp （YH3-type）→Cmcm of ScH3 is predicted first; the corresponding transition pressures at 0 K are 23 GPa, 25 GPa, 348 GPa, and 477 GPa, respectively. The C2/m symmetry structure is a possible candidate but not a good one as the intermediate state from hexagonal to cubic in ScH3. On the other hand, via the analysis of the structures of hexagonal SCH2.9, cubic ScH3, and cubic ScH2, we find that the repulsive interactions of H-H atoms must play an important role in the transition from hexagonal to cubic.

关键词： ab-initio calculations phase transitions high pressure

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Quantitative structure-property relationship study of cathode volume changes in lithium ion batteries using ab-initio and partial least squares analysis

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Journal of Materiomics 2017年第3期3卷 178-183页

作者： Xuelong Wang Ruijuan Xiao Hong Li Liquan Chen Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China

In this paper,we report a method through the combination of ab-initio calculations and partial least squares(PLS)analysis to develop the Quantitative Structure eActivity Relationship(QSAR)formulations of cathode volume changes in lithium ion batteries.The PLS analysis is based on ab-initio calculation data of 14 oxide cathodes with spinel structure LiX2O4 and 14 oxide cathodes with layered-structure LiXO_(2)(X=Ti,V,Cr,Mn,Fe,Co,Ni,Nb,Mo,Ru,Rh,Pd,Ta,Ir).Five types of descriptors,describing the characteristics of each compound from crystal structure,element,composition,local distortion and electronic level,with 34 factors in total,are adopted to obtain the QSAR formulation.According to the variable importance in projection analysis,the radius of X4t ion,and the X octahedron descriptors make major contributions to the volume change of cathode during delithiation.The analysis is hopefully applied to the virtual screening and combinatorial design of low-strain cathode materials for lithium ion batteries.

关键词： Low-strain cathode Lithium ion battery ab-initio calculations Partial least squares regression QSAR

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Dynamic structure change of Cu nanoparticles on carbon supports for CO_(2) electro-reduction toward multicarbon products

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InfoMat 2021年第11期3卷 1285-1294页

作者： Qiang Li Yehui Zhang Li Shi Mingliang Wu Yixin Ouyang Jinlan Wang School of Physics Southeast UniversityNanjingChina

Cu nanoparticles with different sizes,morphology,and surface structures exhibit distinct activity and selectivity toward CO_(2) reduction reaction,while the reactive sites and reaction mechanisms are very controversial in experiments.In this study,we demonstrate the dynamic structure change of Cu clusters on graphite-like carbon supports plays an important role in the multicarbon production by combining static calculations and ab-initio molecular dynamic simulations.The mobility of Cu clusters on graphite is attributed to the near-degenerate energies of various adsorption configurations,as the interaction between Cu atoms and surface C atoms is weaker than that of Cu-Cu bonds in the tight cluster form.Such structure change of Cu clusters leads to step-like irregular surface structures and appropriate interparticle distances,increasing the selectivity of multicarbon products by reducing the energy barriers of C-C coupling effectively.In contrast,the large ratio of edge and corner sites on Cu clusters is responsible for the increased catalytic activity and selectivity for CO and H_(2) compared with Cu(100)surface,instead of hydrocarbon products like methane and ethylene.The detailed study reveals that the dynamic structure change of the catalysts results in roughened surface morphologies during catalytic reactions and plays an essential role in the selectivity of CO_(2) electro-reduction,which should be paid more attention for studies on the reaction mechanisms.

关键词： ab-initio calculations CO_(2)electro-reduction reaction Cu clusters dynamic structure change multicarbon products

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A Study by ab-initio Calculation of Structural and Electronic Properties of Semiconductor Nanostructures Based on ZnSe

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Materials Sciences and Applications 2016年第9期7卷 562-573页

作者： A. Rachidi E. H. Atmani N. Fazouan M. Boujnah Department of Physics Faculty of Sciences and Techniques Hassan II University Casablanca Morocco Department of Physics Faculty of Sciences and Techniques Sultan Moulay Slimane University Beni Mellal Morocco Department of Physics Faculty of Sciences Mohamed V University Rabat Morocco

Our calculations are based on the modeling technique and simulation ab-initio that appeals to the Density Functional Theory (DFT) relying on the Full-Potential Linearized Augmented Plane Waves (FP-LAPW) method that requires a calculation process using approximations such as Local Density (LDA) and Generalized Gradient (GGA) developed in the modelling software of nanostructures WIEN2k. The optimal structure of the binary semiconductor ZnSe crystallizing in the complex phase of Zinc Blende (B3) was determined by studying the variation of energy depending on the volume of the elementary cell. Then the electronic properties of the optimized state were analyzed such as the gap energy, the total density of states (TDOS), the partial density of states (PDOS) and the repartition of the electronic charge density. The obtained results were successful compared with other theoretical and experimental values reported in literature.

关键词： ZnSe ab-initio calculations Density Functional Theory Band Gap Energy Density of States Electronic Charge Density

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