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金属表面缓蚀剂自组装单分子膜的STM研究进展 Ⅰ.惰性金属表面的缓蚀剂自组装单分子膜 被引量:12
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作者 孔德生 万立骏 +1 位作者 陈慎豪 杨武 《腐蚀与防护》 CAS 2003年第10期415-420,共6页
简要介绍了扫描隧道显微镜(STM)技术的基本工作原理及其在表面原子/分子结构研究中的独特优势。缓蚀剂分子对基底金属的保护和抗腐蚀作用,是自组装单分子膜(SAMs)应用中的一个非常重要的方面。本文综述了STM对金属表面缓蚀剂自组装单分... 简要介绍了扫描隧道显微镜(STM)技术的基本工作原理及其在表面原子/分子结构研究中的独特优势。缓蚀剂分子对基底金属的保护和抗腐蚀作用,是自组装单分子膜(SAMs)应用中的一个非常重要的方面。本文综述了STM对金属表面缓蚀剂自组装单分子膜的结构、性质、晶面结构效应等方面的最新研究进展。 展开更多
关键词 扫描隧道显微镜 缓蚀剂 自组装单分子膜 二维晶格
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二维材料/铁电异质结构的研究进展 被引量:15
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作者 王慧 徐萌 郑仁奎 《物理学报》 SCIE EI CAS CSCD 北大核心 2020年第1期175-198,共24页
二维材料是一类具有原子层厚度的层状材料,拥有独特的电学、磁学、光学和力学性能.以石墨烯和过渡金属硫族化合物为代表的二维材料展现出迁移率高、能带可调、可见光透过率高等特点,是近年来微纳科学领域的前沿热点.将二维材料与各种功... 二维材料是一类具有原子层厚度的层状材料,拥有独特的电学、磁学、光学和力学性能.以石墨烯和过渡金属硫族化合物为代表的二维材料展现出迁移率高、能带可调、可见光透过率高等特点,是近年来微纳科学领域的前沿热点.将二维材料与各种功能材料,如SiO2绝缘体、半导体、金属、有机化合物等结合,可以深化和拓宽二维材料的基础研究和应用.其中,铁电材料因具有自发极化、高介电常数、高压电系数等优点吸引了众多研究者的目光.二维/铁电复合材料很好地兼顾了二者的优点,不仅包含了磁电耦合效应、铁电场效应、晶格应变效应、隧穿效应、光电效应、光致发光效应等丰富的物理现象,而且在多态存储器、隧穿晶体管、光电二极管、太阳能电池、超级电容器、热释电红外探测器等器件中有广阔的应用前景,引起了学术界的广泛关注.本文选取典型的二维/铁电复合材料,重点介绍了这类材料界面处的物理机制、材料的性能以及应用前景,并对二维/铁电复合材料的研究进行了展望. 展开更多
关键词 二维材料 铁电材料 晶格应变效应 铁电场效应
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Lattice vibrations and Raman scattering in two- dimensional layered materials beyond graphene 被引量:11
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作者 Xin Lu Xin Luo +2 位作者 Jun Zhang Su Ying Quek Qihua Xiong 《Nano Research》 SCIE EI CAS CSCD 2016年第12期3559-3597,共39页
We review lattice vibrational modes in atomically thin two-dimensional (2D) layered materials, focusing on 2D materials beyond graphene, such as group VI transition metal dichalcogenides, topological insulator bismu... We review lattice vibrational modes in atomically thin two-dimensional (2D) layered materials, focusing on 2D materials beyond graphene, such as group VI transition metal dichalcogenides, topological insulator bismuth chalcogenides, and black phosphorus. Although the composition and structure of those materials are remarkably different, they share a common and important feature, i.e., their bulk crystals are stacked via van der Waals interactions between "layers", while each layer is comprised of one or more atomic planes. First, we review the background of some 2D materials (MX2, M = Mo, W; X = S, Se, Te. Bi2X3, X = Se, Te. Black phosphorus), including crystalline structures and stacking order. We then review the studies on vibrational modes of layered materials and nanostructures probed by the powerful yet nondestructive Raman spectroscopy technique. Based on studies conducted before 2010, recent investigations using more advanced techniques have pushed the studies of phonon modes in 2D layered materials to the atomically thin regime, down to monolayers. We will classify the recently reported general features into the following categories: phonon confinement effects and electron-phonon coupling, anomalous shifts in high-frequency intralayer vibrational modes and surface effects, reduced dimensionality and lower symmetry, the linear chain model and the substrate effect, stacking orders and interlayer shear modes, polarization dependence, and the resonance effect. Within the seven categories, both intralayer and interlayer vibrational modes will be discussed. The comparison between different materials will be provided as well. 展开更多
关键词 PHONON lattice vibration Raman spectroscopy two-dimensional transition metaldichalcogenide black phosphorus
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Classical spin liquid state in a rhombic lattice metal-organic framework
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作者 Sihua Feng Chao Wang +8 位作者 Jiyin Zhao Xuguang Liu Chaocheng Liu Zeming Qi Lei Chen Huijuan Wang Minghui Fan Hengli Duan Wensheng Yan 《Nano Research》 SCIE EI CSCD 2024年第4期3407-3412,共6页
Discovering more and new geometrically frustrated systems remains an active point of inquiry in fundamental physics for the existence of unusual states of matter.Here,we report spin-liquid-like behavior in a two-dimen... Discovering more and new geometrically frustrated systems remains an active point of inquiry in fundamental physics for the existence of unusual states of matter.Here,we report spin-liquid-like behavior in a two-dimensional(2D)rhombic lattice Fe-metal-organic framework(Fe-MOF)with frustrated antiferromagnetism.This Fe-MOF exhibits a high frustration factor f=|θCW|/TN≥315,and its long-range magnetic order is suppressed down to 180 mK.Detailed theoretical calculations demonstrate strong antiferromagnetic coupling between adjacent Fe3+ions,indicating the potential of a classical spin-liquid-like behavior.Notably,a T-linear heat capacity parameter,γ,originating from electronic contributions and with magnetic field independence up to 8 T,can be observed in the specific heat capacity measurements at low-temperature,providing further proof for the spin-liquid-like behavior.This work highlights the potential of MOF materials in geometrically frustrated systems,and will promote the research of exotic quantum physics phenomena. 展开更多
关键词 spin-liquid-like state two-dimensional metal-organic framework(2D MOF) rhombic lattice ultralow temperature(ULT)measurements spin-frustrated
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摩擦力显微镜表征二维材料晶格结构研究 被引量:3
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作者 郑荣戌 王经纬 +7 位作者 张云豪 农慧雨 吴沁柯 武科佑 谭隽阳 黄子阳 余强敏 刘碧录 《科学通报》 EI CAS CSCD 北大核心 2023年第22期2924-2933,共10页
摩擦力显微镜(friction force microscopy,FFM)是一种基于摩擦力信号的原子力显微镜,能够对二维材料晶格进行快速、无损的高分辨成像.然而,由于热漂移、黏附力、表面静电等因素的影响,环境条件下二维材料的高分辨FFM成像仍面临着巨大挑... 摩擦力显微镜(friction force microscopy,FFM)是一种基于摩擦力信号的原子力显微镜,能够对二维材料晶格进行快速、无损的高分辨成像.然而,由于热漂移、黏附力、表面静电等因素的影响,环境条件下二维材料的高分辨FFM成像仍面临着巨大挑战.基于以上问题,本文以高定向热解石墨为标准样品,通过对探针在样品表面黏滑行为的分析,系统研究了探针弹性常数、正应力和扫描速度对高分辨FFM成像的影响,并建立了一套可靠的二维材料晶格结构表征方法.该方法能够获得精确的结构信息,所测得的二维材料晶格常数平均误差小于2.3%.此外,该方法还适用于化学气相沉积法和剥离法制备的多种二维材料,展现出较高的普适性.本文的研究结果为环境条件下二维材料晶格结构的精确表征提供了新思路. 展开更多
关键词 二维材料 摩擦力显微镜 高分辨结构表征 晶格常数 石墨烯 二维矿物材料
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Lattice vibration and Raman scattering of two-dimensional van der Waals heterostructure 被引量:1
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作者 Xin Cong Miaoling Lin Ping-Heng Tan 《Journal of Semiconductors》 EI CAS CSCD 2019年第9期13-19,共7页
Research on two-dimensional(2D) materials and related van der Waals heterostructures(vdWHs) is intense and remains one of the leading topics in condensed matter physics.Lattice vibrations or phonons of a vdWH provide ... Research on two-dimensional(2D) materials and related van der Waals heterostructures(vdWHs) is intense and remains one of the leading topics in condensed matter physics.Lattice vibrations or phonons of a vdWH provide rich information,such as lattice structure,phonon dispersion,electronic band structure and electron–phonon coupling.Here,we provide a mini review on the lattice vibrations in vdWHs probed by Raman spectroscopy.First,we introduced different kinds of vdWHs,including their structures,properties and potential applications.Second,we discussed interlayer and intralayer phonon in twist multilayer graphene and MoS2.The frequencies of interlayer and intralayer modes can be reproduced by linear chain model(LCM)and phonon folding induced by periodical moiré potentials,respectively.Then,we extended LCM to vdWHs formed by distinct 2D materials,such as MoS2/graphene and hBN/WS2 heterostructures.We further demonstrated how to calculate Raman intensity of interlayer modes in vdWHs by interlayer polarizability model. 展开更多
关键词 two-dimensional materials VAN der WAALS HETEROSTRUCTURE Raman spectroscopy lattice vibration PHONON
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Design and analysis of superlens based on complex two-dimensional square lattice photonic crystal 被引量:2
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作者 Somayeh Rafiee Dastjerdi Majid Ghanaatshoar Toshiaki Hattori 《Chinese Optics Letters》 SCIE EI CAS CSCD 2013年第10期83-86,共4页
We theoretically demonstrate the imaging properties of a complex two-dimensional(2D) face-centered square lattice photonic crystal(PC) made from germanium cylinders in air background. The finitedifference time-domain(... We theoretically demonstrate the imaging properties of a complex two-dimensional(2D) face-centered square lattice photonic crystal(PC) made from germanium cylinders in air background. The finitedifference time-domain(FDTD) method is employed to calculate the band structure and simulate image construction. The band diagram of the complex structure is significantly compressed. Negative refraction occurs in the second energy band with negative phase velocity at a frequency of 0.228(2πc/a), which is lower than results from previous studies. Lower negative refraction frequency leads to higher image resolution. Numerical results show that the spatial resolution of the system reaches 0.7296λ, which is lower than the incident wavelength. 展开更多
关键词 Design and analysis of superlens based on complex two-dimensional square lattice photonic crystal
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一类两维光学格子中稳定的复合孤子 被引量:1
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作者 董亮伟 叶芳伟 +1 位作者 王建东 李永平 《物理学报》 SCIE EI CAS CSCD 北大核心 2005年第9期4458-4462,共5页
对两维光学格子中非线性薛定谔方程一类新的稳态解做了数值分析,发现其在传播过程中逐渐衰变为一种稳定的复合孤子,孤子的两分量在传播过程中不断交换能量,总能量守恒.
关键词 稳态解 两维格子 孤子 光学格子 复合 两维 非线性薛定谔方程 总能量守恒 传播过程 数值分析
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飞秒化学研究进展 被引量:2
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作者 陆云清 《激光与光电子学进展》 CSCD 北大核心 2008年第9期38-46,共9页
飞秒超快激光技术为物理、化学、生物学和材料等领域提供了一种新颖的工具,使研究人员可以研究其中发生的超快过程,对当今的高科技和相应产业,如超快光通信、新型有机无机材料、分子生物学、基因工程等的研究和发展也具有重要意义。介... 飞秒超快激光技术为物理、化学、生物学和材料等领域提供了一种新颖的工具,使研究人员可以研究其中发生的超快过程,对当今的高科技和相应产业,如超快光通信、新型有机无机材料、分子生物学、基因工程等的研究和发展也具有重要意义。介绍了飞秒化学的最新进展,包括优化整形脉冲对化学反应的控制、飞秒位相相干二维光谱、晶格振动波的时空相干控制等。 展开更多
关键词 飞秒化学 二维光谱 晶格振动波 优化整形脉冲
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Two-Dimensional Node-Line Semimetals in a Honeycomb-Kagome Lattice 被引量:2
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作者 卢金炼 罗伟 +4 位作者 李雪阳 杨晟祺 曹觉先 龚新高 向红军 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第5期106-110,共5页
Recently, the concept of topological insulators has been generalized to topological semimetals, including three-dimensional (3D) Weyl semimetals, 3D Dirac semimetMs, and 3D node-line semimetals (NLSs). In particul... Recently, the concept of topological insulators has been generalized to topological semimetals, including three-dimensional (3D) Weyl semimetals, 3D Dirac semimetMs, and 3D node-line semimetals (NLSs). In particular, several compounds (e.g., certain 3D graphene networks, Cu3PdN, Ca3P2 ) were discovered to be 3D NLSs, in which the conduction and valence bands cross at closed lines in the Brillouin zone. Except for the two-dimensional (2D) Dirac semimetal (e.g., graphene), 2D topological semimetals are much less investigated. Here we propose a new concept of a 2D NLS and suggest that this state could be realized in a new mixed lattice (named as HK lattice) composed by Kagome and honeycomb lattices. It is found that A3B2 (A is a group-liB cation and B is a group-VA anion) compounds (such as Hg3As2) with the HK lattice are 2D NLSs due to the band inversion between the cation Hg-s orbital and the anion As-pz orbital with respect to the mirror symmetry. Since the band inversion occurs between two bands with the same parity, this peculiar 2D NLS could be used as transparent conductors. In the presence of buckling or spin-orbit coupling, the 2D NLS state may turn into a 2D Dirac semimetal state or a 2D topological crystalline insulating state. Since the band gap opening due to buckling or spin-orbit coupling is small, Hg3As3 with the HK lattice can still be regarded as a 2D NLS at room temperature. Our work suggests a new route to design topological materials without involving states with opposite parities. 展开更多
关键词 As HG NLS two-dimensional Node-Line Semimetals in a Honeycomb-Kagome lattice
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Two-dimensional Dirac materials:Tight-binding lattice models and material candidates 被引量:1
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作者 Runyu Fan Lei Sun +2 位作者 Xiaofei Shao Yangyang Li Mingwen Zhao 《ChemPhysMater》 2023年第1期30-42,共13页
The discovery of graphene has led to the devotion of intensive efforts,theoretical and experimental,to produce two-dimensional(2D)materials that can be used for developing functional materials and devices.This work pr... The discovery of graphene has led to the devotion of intensive efforts,theoretical and experimental,to produce two-dimensional(2D)materials that can be used for developing functional materials and devices.This work provides a brief review of the recent developments in the lattice models of 2D Dirac materials and their relevant real material counterparts that are crucial for understanding the origins of 2D Dirac cones in electronic band structures as well as their material design and device applications.We focus on the roles of lattice symmetry,atomic orbital hybridization,and spin-orbit coupling in the presence of a Dirac cone.A number of lattice models,such as honeycomb,kagome,ruby,star,Cairo,and line-centered honeycomb,with different symmetries are reviewed based on the tight-binding approach.Inorganic and organic 2D materials,theoretically proposed or experimentally synthesized to satisfy these 2D Dirac lattice models,are summarized. 展开更多
关键词 Dirac cones two-dimensional materials Tight-binding model lattice models
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Coexistence of Quasi-two-dimensional Superconductivity and Tunable Kondo Lattice in a van der Waals Superconductor 被引量:1
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作者 Shiwei Shen Tian Qin +8 位作者 Jingjing Gao Chenhaoping Wen Jinghui Wang Wei Wang Jun Li Xuan Luo Wenjian Lu Yuping Sun Shichao Yan 《Chinese Physics Letters》 SCIE EI CAS CSCD 2022年第7期81-86,共6页
Realization of Kondo lattice in superconducting van der Waals materials not only provides a unique opportunity for tuning the Kondo lattice behavior by electrical gating or intercalation,but also is helpful for furthe... Realization of Kondo lattice in superconducting van der Waals materials not only provides a unique opportunity for tuning the Kondo lattice behavior by electrical gating or intercalation,but also is helpful for further understanding the heavy fermion superconductivity.Here we report a low-temperature and vector-magneticfield scanning tunneling microscopy and spectroscopy study on a superconducting compound(4Hb-TaS_(2))with alternate stacking of 1T-TaS_(2)and 1H-TaS_(2)layers.We observe the quasi-two-dimensional superconductivity in the 1H-TaS_(2)layer with anisotropic response to the in-plane and out-of-plane magnetic fields.In the 1T-TaS_(2)layer,we detect the Kondo resonance peak that results from the Kondo screening of the unpaired electrons in the Star-of-David clusters.We also find that the intensity of the Kondo resonance peak is sensitive to its relative position with the Fermi level,and it can be significantly enhanced when it is further shifted towards the Fermi level by evaporating Pb atoms onto the 1T-TaS_(2)surface.Our results not only are important for fully understanding the electronic properties of 4Hb-TaS_(2),but also pave the way for creating tunable Kondo lattice in the superconducting van der Waals materials. 展开更多
关键词 red Coexistence of Quasi-two-dimensional Superconductivity and Tunable Kondo lattice in a van der Waals Superconductor lattice
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Two-Dimensional Breather Lattice Solutions and Compact-Like Discrete Breathers and Their Stability in Discrete Two-Dimensional Monatomic β-FPU Lattice
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作者 XU Quan TIAN Qiang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第1期153-156,共4页
We restrict our attention to the discrete two-dimensional monatomic β-FPU lattice. We look for two- dimensional breather lattice solutions and two-dimensional compact-like discrete breathers by using trying method an... We restrict our attention to the discrete two-dimensional monatomic β-FPU lattice. We look for two- dimensional breather lattice solutions and two-dimensional compact-like discrete breathers by using trying method and analyze their stability by using Aubry's linearly stable theory. We obtain the conditions of existence and stability of two-dimensional breather lattice solutions and two-dimensional compact-like discrete breathers in the discrete two- dimensional monatomic β-FPU lattice. 展开更多
关键词 β-FPU lattice two-dimensional breather lattice solution two-dimensional compact-like discrete breather
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Transport induced dimer state from topological corner states 被引量:1
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作者 Kai-Tong Wang Yafei Ren +2 位作者 Fuming Xu Yadong Wei Jian Wang 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2021年第5期91-96,共6页
Recently, a new type of second-order topological insulator has been theoretically proposed by introducing an in-plane Zeeman field into the Kane-Mele model in the two-dimensional honeycomb lattice. A pair of topologic... Recently, a new type of second-order topological insulator has been theoretically proposed by introducing an in-plane Zeeman field into the Kane-Mele model in the two-dimensional honeycomb lattice. A pair of topological corner states arise at the corners with obtuse angles of an isolated diamond-shaped flake. To probe the corner states, we study their transport properties by attaching two leads to the system. Dressed by incoming electrons, the dynamic corner state is very different from its static counterpart.Resonant tunneling through the dressed corner state can occur by tuning the in-plane Zeeman field. At the resonance, the pair of spatially well separated and highly localized corner states can form a dimer state, whose wavefunction extends almost the entire bulk of the diamond-shaped flake. By varying the Zeeman field strength, multiple resonant tunneling events are mediated by the same dimer state. This re-entrance effect can be understood by a simple model. These findings extend our understanding of dynamic aspects of the second-order topological corner states. 展开更多
关键词 higher-order topological insulators multiple resonant tunneling in-plane Zeeman field two-dimensional honeycomb lattice
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Group 14 element-based non-centrosymmetric quantum spin Hall insulators with large bulk gap 被引量:1
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作者 Yandong Ma Liangzhi Kou +1 位作者 Aijun Du Thomas Heine 《Nano Research》 SCIE EI CAS CSCD 2015年第10期3412-3420,共9页
To date, a number of two-dimensional (2D) topological insulators (TIs) have been realized in Group 14 elemental honeycomb lattices, but all are inversionsymmetric. Here, based on first-principles calculations, we ... To date, a number of two-dimensional (2D) topological insulators (TIs) have been realized in Group 14 elemental honeycomb lattices, but all are inversionsymmetric. Here, based on first-principles calculations, we predict a new family of 2D inversion-asymmetric TIs with sizeable bulk gaps from 105 meV to 284 meV, in X2-GeSn (X = H, F, Cl, Br, I) monolayers, making them in principle suitable for room-temperature applications. The nontrivial topological characteristics of inverted band orders are identified in pristine X2-GeSn with X = (F, Cl, Br, I), whereas H2-GeSn undergoes a nontrivial band inversion at 8% lattice expansion. Topologically protected edge states are identified in X2-GeSn with X = (F, Cl, Br, I), as well as in strained H2-GeSn. More importantly, the edges of these systems, which exhibit single-Dirac-cone characteristics located exactly in the middle of their bulk band gaps, are ideal for dissipationless transport. Thus, Group 14 elemental honeycomb lattices provide a fascinating playground for the manipulation of quantum states. 展开更多
关键词 two-dimensional crystal topological insulators Dirac states band inversion strain engineering Group 14 honeycomb lattice
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二维晶格色散关系和态密度的紧束缚模型计算 被引量:1
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作者 王妮娜 路洪艳 +4 位作者 魏梦俊 徐慧 刘晓静 张娇娇 胡新春 《淮北师范大学学报(自然科学版)》 CAS 2014年第4期12-16,共5页
文章利用紧束缚模型计算了二维正方、三角、六角格子色散关系.对于正方和三角格子,主要考虑电子在最近邻格点上的跳跃情况.对于六角格子,以石墨烯为例,考虑电子只在最近邻格点上跳跃以及同时考虑电子在最近邻和次近邻格点上跳跃两种情况... 文章利用紧束缚模型计算了二维正方、三角、六角格子色散关系.对于正方和三角格子,主要考虑电子在最近邻格点上的跳跃情况.对于六角格子,以石墨烯为例,考虑电子只在最近邻格点上跳跃以及同时考虑电子在最近邻和次近邻格点上跳跃两种情况.对于以上3种格子的色散关系,利用Matlab软件进行图形化,并用Fortran软件编程计算相应的态密度,计算结果对理解不同晶格的电学性质提供理论基础. 展开更多
关键词 紧束缚模型 哈密顿量 二维晶格 色散关系 态密度
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二维网格上经纪人模仿引起的自组织分离与聚合
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作者 杨伟松 杨德军 《湖北文理学院学报》 2014年第5期21-23,共3页
将"演化的争当少数者博弈"模型(EMG)建立在41×41的二维正方形网格上,格点代表经纪人,连线代表该两相邻经纪人存在联系,每个经纪人被随机分配一个介于0与1之间的基因策略p值。数值模拟结果表明:模型的奖惩比等于或大于1时... 将"演化的争当少数者博弈"模型(EMG)建立在41×41的二维正方形网格上,格点代表经纪人,连线代表该两相邻经纪人存在联系,每个经纪人被随机分配一个介于0与1之间的基因策略p值。数值模拟结果表明:模型的奖惩比等于或大于1时,随着演化过程的进行,系统经纪人倾向于模仿具有极端基因策略值(接近0或1)经纪人的策略,说明极端的决定策略比犹豫策略(接近0.5)的表现要好,能使经纪人获得更大收益;当经纪人策略自组织分离现象出现后,人群-反人群效应更加明显,系统一方人数的变化偏差显著降低,系统资源得到更加有效的利用.而当模型的奖惩比小于1时,即处于困难时期时,中间犹豫策略的表现则比极端策略要好. 展开更多
关键词 EMG模型 二维网格 经纪人模仿 人群-反人群效应 自组织分离与聚合
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A CA-LBM model for simulating dendrite growth with forced convection
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作者 Xiang-ning Meng Lei Cui +1 位作者 Yi-han Shi Miao-yong Zhu 《Journal of Iron and Steel Research International》 SCIE EI CSCD 2021年第8期997-1008,共12页
A two-dimensional coupled model of the cellular automaton(CA)and the lattice Boltzmann method(LBM)was developed to simulate the solute dendrite growth of Fe-C-Mn-S alloy in the presence of forced convection.The model ... A two-dimensional coupled model of the cellular automaton(CA)and the lattice Boltzmann method(LBM)was developed to simulate the solute dendrite growth of Fe-C-Mn-S alloy in the presence of forced convection.The model describes the transport phenomenon by the evolution of moving pseudo-particles distribution functions and utilizes the LBM to solve fluid flow and solute transport under forced convection numerically.Based on the solute field calculated by the CA technique,the dynamics of dendrite growth were determined by the previously proposed local solute balance method.The accuracy of the forced convection dendrite growth model was verified by comparing the CA-LBM model with Lipton-Glicksman-Kurz analytical model.It is revealed that the dendrite symmetry structure is destroyed compared to free diffusion,and the upstream arm is more developed than the downstream arm of the dendrite.The enriched solute segregates more at the downstream side than at the upstream side of the dendrite.The length of the upstream dendrite arm increases firstly and then becomes stable with the increase in the flow velocity,the dendrite necking is restrained,and the vertical dendrite arm becomes longer. 展开更多
关键词 two-dimensional coupled model Cellular automaton lattice Boltzmann method Dendrite growth Forced convection
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有限图上的量子游荡的相关性质
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作者 韩琦 陈芷禾 +1 位作者 殷世德 陆自强 《应用概率统计》 CSCD 北大核心 2020年第4期365-380,共16页
基于Fourier变换,我们得到了有限图上的量子游荡的解析解相关性质.主要包括环上的量子游荡一般态解析解的性质、二维晶格上的特殊量子游荡的无偏性及其超立方体上的量子游荡初始条件与不变子空间的一组基之间的关系.
关键词 量子行走 傅里叶变换 二维晶格 超立方体
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Prediction of a large-gap quantum-spin-Hall insulator: Diamond-like GaBi bilayer
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作者 Aizhu Wang Aijun Du Mingwen Zhao 《Nano Research》 SCIE EI CAS CSCD 2015年第12期3823-3829,共7页
A quantum-spin-Hall (QSH) state was achieved experimentally, albeit at a low critical temperature because of the narrow band gap of the bulk material. Two- dimensional topological insulators are critically important... A quantum-spin-Hall (QSH) state was achieved experimentally, albeit at a low critical temperature because of the narrow band gap of the bulk material. Two- dimensional topological insulators are critically important for realizing novel topological applications. Using density functional theory (DFT), we demonstrated that hydrogenated GaBi bilayers (HGaBi) form a stable topological insulator with a large nontrivial band gap of 0.320 eV, based on the state-of-the-art hybrid functional method, which is implementable for achieving QSH states at room temperature. The nontrivial topological property of the HGaBi lattice can also be confirmed from the appearance of gapless edge states in the nanoribbon structure. Our results provide a versatile platform for hosting nontrivial topological states usable for important nanoelectronic device applications. 展开更多
关键词 topological insulators first-principles calculations two-dimensional cubic-diamond-like lattice Rashba spin splitting band inversion
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