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Structure stability and configuration evolution of Al_n(n=3, 4, 6, 13, 19) clusters

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Science China(Technological Sciences) 2006年第4期49卷 385-392页

作者： PENG Ping LI Guifa ZHENG caixing HAN Shaochang liu Rangsu School of Materials Science and Engineering Hunan University Changsha 410082 China School of Materials Science and Engineering Hunan University Changsha 410082 China School of Materials Science and Engineering Hunan University Changsha 410082 China School of Materials Science and Engineering Hunan University Changsha 410082 China School of Materials Science and Engineering Hunan University Changsha 410082 China

Using a first-principles pseudo-potential plane wave method, the geometrical and electronic structures of Aln (n=3, 4, 6, 13, 19) clusters with different configurations have been calculated. Several parameters such as the binding energy Eb and the HOMO-LUMO energy gap ?EH-L have been adopted to characterize and analyze the structure stability of these clusters, and their configuration evolutions are also investigated by linear synchronous transit (LST) method. It is demonstrated that the stable configura- tions of Al3, Al4, Al6, Al13, Al19 clusters are triangle, rhombus, octahedron, icosahedron and double icosahedron, respectively. For Al6 and Al19 clusters there are metastable structures of parallelogram and octahedron, respectively, whereas in the Al3, Al4 and Al13 clusters, no metastable configuration is validated. There exist a large energy gap and a low energy barrier between the octahedron and the parallelogram of the Al6 cluster, so the transfor- mation from its metastable to stable structures is rather easy. By contrast, a small energy gap and a high energy barrier between the stable and metastable structures of Al19 cluster mean its configuration evolution from the octahedron to the double icosahedron occurs hardly, therefore the metastable octahedron configuration of Al19 cluster can be extensively detected in experiments and simulations.

关键词： first-principles calculation, Al cluster, configuration evolution.

A simulation study of rapid solidification and crystal configuration of Cu_(70)Ni_(30) alloy

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Science China(Physics,Mechanics & Astronomy) 2005年第6期48卷 687-694页

作者： ZHENG caixing liu Rangsu ZHOU Qunyi TIAN Ze'an WANG Xin LI Qiang Department of Physics Hunan University Changsha 410082 China Department of Physics Hunan University Changsha 410082 China Department of Physics Hunan University Changsha 410082 China Department of Physics Hunan University Changsha 410082 China Department of Physics Hunan University Changsha 410082 China Department of Physics Hunan University Changsha 410082 China

A molecular dynamics (MD) simulation study has been performed for the rapid solidification of Cu70Ni30 adopting the quantum Sutton-Chen many-body potentials. By analyzing the bond-types and the relation of atomic average energy versus temperature, it was demonstrated that as cooling rate being 2 × 1012 K/s, the Cu70Ni30 formed fcc crystal structures and freezing point was found. In addition, having analyzed the transformation of microstructures and the detail of crystal growth by using atomic trace and visual method, not only could the formation of binary disordered solid solution be showed, but also the solidification of liquid metals and the crystal growth processes could be further understood.

关键词： quantum Sutton-Chen potentials, molecular dynamics simulation, Cu70Ni30 alloy, rapid solidification.

Planar-symmetry-breaking induced antisymmetric magnetoresistance in van der Waals ferromagnet Fe_(3)GeTe_(2)

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Nano Research 2022年第3期15卷 2531-2536页

作者： Ping liu caixing liu Zhi Wang Meng Huang Guojing Hu Junxiang Xiang Chao Feng Chen Chen Zongwei Ma Xudong Cui Hualing Zeng Zhigao Sheng Yalin Lu Gen Yin Gong Chen Kai liu Bin Xiang Hefei National Laboratory for Physical Sciences at the Microscale Department of Materials Science&EngineeringCAS Key Lab of Materials for Energy ConversionUniversity of Science and Technology of ChinaHefei 230026China School of Science Nanjing University of Posts and TelecommunicationsNanjing 210023China Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field LaboratoryChinese Academy of SciencesHefei 230031China Sichuan New Materials Research Center Institute of Chemical MaterialsCAEPChengdu 610200China Anhui Laboratory of Advanced Photon Science and Technology University of Science and Technology of ChinaHefei 230026China Physics Department Georgetown UniversityWashingtonDC 20057USA

Recently discovered magnetic van der Waals(vdW)materials provide an ideal platform to explore low-dimensional magnetism and spin *** vdW interaction nature opens up unprecedented opportunities to build vertically stacked heterostructures with novel properties and *** engineering the planar structure as an alternative degree of freedom,herein we demonstrate an antisymmetric magnetoresistance(MR)in a vdW Fe_(3)GeTe_(2)flake with a step terrace that breaks the planar *** antisymmetric MR originates from a sign change of the anomalous Hall effect and the continuity of the current transport near the boundary of magnetic domains at the step edge.A repeatable domain wall due to the unsynchronized magnetization switching is responsible for this sign *** interpretation is supported by the observation of field-dependent domain switching,and the step thickness,temperature,and magnetic field orientation dependent *** work opens up new opportunities to encode magnetic information by controlling the planar domain structures in vdW magnets.

关键词： 2D magnetism Fe_(3)GeTe_(2) planar structure engineering antisymmetric magnetoresistance

Evidence for distortion-induced local electric polarization in α-RuCl_(3)

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Science China(Physics,Mechanics & Astronomy) 2024年第9期67卷 165-173页

作者： Xinrun Mi De Hou Xiao Wang Sabreen Hammouda caixing liu Zijian Xiong Han Li Yan liu Guiwen Wang Aifeng Wang Yisheng Chai Yang Qi Wei Li Xiaoyuan Zhou Yixi Su DIKhomskii Mingquan He Zhigao Sheng Young Sun College of Physics Center of Quantum Materials and DevicesChongqing UniversityChongqing 401331China Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field LaboratoryHefei Institutes of Physical ScienceAnhuiChinese Academy of SciencesHefei 230031 China University of Science and Technology of China Hefei 230026China Jülich Centre for Neutron Scienceat Heinz Maier-Leibnitz Zentrum(JCNS-MLZ) Forschungszentrum Jülich GmbHGarching D-85747Germany School of Physics Beihang UniversityBeijing 100191China Analytical and Testing Center Chongqing UniversityChongqing 401331China State Key Laboratory of Surface Physics Department of PhysicsFudan UniversityShanghai 200433China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China Ⅱ.Physikalisches Institut Universität zu KölnKöln D-50937Germany

The spin-orbit assisted Mott insulator α-RuCl_(3) is a prime candidate for material realization of the Kitaev quantum spin *** little attention has been paid to charge degrees of freedom,charge effects,such as electric polarization,may arise in this ***,we report distortion-induced local electric polarization in α-RuCl_(3) as evidenced by single-crystal X-ray diffraction,second harmonic generation(SHG)and dielectric *** SHG signal appears at room temperature and develops substantially in the Kitaev paramagnetic state when short-range spin correlations come into *** sizable pyroelectric currents in the Kitaev paramagnetic state,the absence of hysteresis in the polarization-electric field(P-E)points to the shortrange nature of electric *** localized electric polarization is likely the result of distortion-induced charge dimerization,achieved through virtual hopping-induced charge *** addition,the electric polarization is boosted by short-range spin correlations via spin-phonon coupling in the Kitaev paramagnetic *** results emphasize the importance of charge degrees of freedom in α-RuCl_(3),which establish a novel platform to investigate charge effects in Kitaev materials.

关键词： Mott insulator Kitaev quantum spin liquid electric polarization

Formation and evolution mechanisms of large-clusters during rapid solidification process of liquid metal Al

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Science China(Physics,Mechanics & Astronomy) 2005年第1期48卷 101-112页

作者： liu Rangsu, DONG Kejun, liu Fengxiang, ZHENG caixing, liu Hairong & LI Jiyong Department of Applied Physics, Hunan University, Changsha 410082, China College of Materials Science and Engineering, Hunan University, Changsha 410082, China College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China 1. Department of Applied Physics Human University 410082 Changsha China 2. College of Materials Science and Engineering Hunan University 410082 Changsha China 3. College of Chemistry and Chemical Engineering Hunan University 410082 Changsha China

A molecular dynamics simulation study has been performed for the formation and evolution characteristics of nano-clusters in a large-scale system consisting of 400000 atoms of liquid metal Al. The center-atom method combined with pair-bond analysis technique and cluster-type index method (CTIM) has been applied here to describe the structural configurations of various basic clusters. It is demonstrated that both the 1551 bond-type and the icosahedral cluster (12 0 12 0) constructed by 1551 bond-types are dominant among all the bond-types and cluster-types, respectively, in the system and play a critical role in the microstructure transitions of liquid metal Al. The nano-clusters (containing up to 150 atoms) are formed by the combination of some middle and small clusters with distinctly different sizes, through mutual competition by unceasing annex and evolution in a seesaw manner (in turn of obtaining and losing),which do not occur as the multi-shell structures accumulated with an atom as the center and the surrounding atoms are arranged according to a certain rule. This is the essential distinction of nano-cluster in liquid metal from those obtained by gaseous deposition, ionic spray methods, and so on. Though the nano-clusters differ from each other in shape and size, all of them possess protruding corners that could become the starting points of various dendrite structures in the solidification processes of liquid metals.

关键词： liquid metal, solidification process, large-cluster configuration, evolution mechanism, computer simulation.

DESIGN OF DATA CENTER’S HIGH RELIABILITY IN LARGE AGRICULTURAL ENTERPRISE

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DESIGN OF DATA CENTER’S HIGH RELIABILITY IN LARGE AGRICULTU...

Size distributions and magic number characteristics of cluster configurations formed during solidification processes of liquid metal Al

Computer and Computing Technologies in Agriculture——First IFIP TC 12 International Conference(CCTA2007) Volume I

作者： Hanxing liu Yingjie Kuang caixing liu Lei Xiao Guomao Xu Department of Computer Science and Engineering South China Agricultural University Informatics Center Guangdong Wen's Food Corporation

It’s necessary for the large agricultural enterprise to construct a stabile and reliable network environment and a powerful Data *** this paper,the constructing of high reliability in Data Center will be discussed according to the requirements of large agricultural enterprise;an effective solution will be presented that adopts structural redundancy and double VPN in the aspect of network and *** solution has been carried out effectively in practical application,and proved that it is an exercisable example for the constructing of Data Center in large agricultural enterprise.

关键词： large agricultural enterprise data center high reliability

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Science China(Technological Sciences) 2006年第2期49卷 172-187页

作者： liu Rangsu1, liu Fengxiang1, DONG Kejun1, ZHENG caixing1, liu Hairong2, PENG Ping2 & LI Jiyong3 1. Department of Physics, Hunan University, Changsha 410082, China 2. Department of Material Science and Engineering, Hunan University, Changsha 410082, China 3. Department of Chemistry, Hunan University, Changsha 410082, China Department of Physics Hunan University Changsha 410082 China Department of Material Science Engineering Hunan University Changsha 410082 China Department of Chemistry Hunan University Changsha 410082 China

A molecular dynamics simulation study has been performed for a large systemconsisting of 100000 liquid metal Al atoms to investigate the formation and magic numbercharacteristics of the cluster configurations formed during the rapid solidification processes. Thecluster-type index method (CTIM) has been adopted to describe various types of clusterconfigurations. The results indicate that the icosahedral clusters (12 0 12 0) and theircombinations play the most important role in the rnicrostructure transitions during solidificationprocesses; for the cluster configurations of different levels formed by various combinations withdiffering numbers of basic clusters, their size distributions possess obvious magic number sequencewhich is in turn as 13(13), 19(21), 26-28(27), 32-33(32), 39-40, 43-44, 48..., (those in bracket arethe corresponding value in liquid state); the magic numbers correspond to the peak value positionsof the cluster numbers for corresponding level formed with various combinations by 1, 2, 3, 4, 5, 6,7, ...basic clusters, respectively. This magic number sequence is in good agreement with theexperimental results obtained by Harris et al. At the same time, this simulation study also gives ascientific and reasonable explanation to these experimental results.

关键词： liquid metal, solidification processes, cluster configuration, magic numbers, computer simulation.

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果树仿形喷雾的虚拟研究

农业工程学报 2007年第7期23卷 133-138页

作者：刘财兴林惠强洪添胜高稳猛华南农业大学信息学院广州510642

鉴于很多研究者只通过试验来定性地研究各种过程参量对喷雾质量的影响,为此作者基于已有的实际试验数据,提出了从理论上对喷雾进行虚拟研究,构建三维空间中的喷雾数学模型,实现了虚拟系统,并对虚拟的结果与实际数据进行分析和对比。结... 详细信息

鉴于很多研究者只通过试验来定性地研究各种过程参量对喷雾质量的影响,为此作者基于已有的实际试验数据,提出了从理论上对喷雾进行虚拟研究,构建三维空间中的喷雾数学模型,实现了虚拟系统,并对虚拟的结果与实际数据进行分析和对比。结果表明,喷雾过程是一个非常复杂而且难以描述的过程。模型能虚拟实际中雾滴在果树中的飞行情况,能够反映实际喷雾的关键元素,可以仿真喷雾沉积分布的趋势。虚拟喷雾模型中设置不同的喷嘴高度,得到的沉积率的趋势一样,说明喷雾高度的变化对结果没有太大的影响。喷雾模型可对开发果树仿形喷雾预测系统或产品提供一定的理论支持。

关键词：仿形喷雾虚拟果树

基于无线传感器网络支持向量机奶牛行为特征识别

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传感技术学报 2011年第3期24卷 458-462页

作者：尹令洪添胜刘迎湖刘财兴华南农业大学信息学院广州510642 华南农业大学工程学院广州510642 华南农业大学理学院广州510642

鉴于我国现有奶牛发情鉴定主要依赖于人工观测、效率低和误判率高的现状,通过给奶牛佩戴嵌入加速度传感器的无线传感节点,实时监测奶牛的行为,并通过基于二叉决策树支持向量机时间序列模型分析加速度数据,逐层分类奶牛的静止、慢走、快... 详细信息

鉴于我国现有奶牛发情鉴定主要依赖于人工观测、效率低和误判率高的现状,通过给奶牛佩戴嵌入加速度传感器的无线传感节点,实时监测奶牛的行为,并通过基于二叉决策树支持向量机时间序列模型分析加速度数据,逐层分类奶牛的静止、慢走、快跑和爬跨行为类型。实验结果表明,该算法对于奶牛轻微和剧烈的运动特征分类准确度达95.5%,研究结果为初步判断奶牛是否发情提供了有效的依据。

关键词：加速度传感器无线传感器网络支持向量机奶牛