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electronic structure calculations of rare-earth intermetallic compound YAg using ab initio methods

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Journal of Rare Earths 2009年第4期27卷 664-666页

作者： S.Ugur G.Ugur F.Soyalp R.Ellialt1oglu Department of Physics Gazi University Teknikokullar Ankara 06500 Turkey Department of Physics Yüzüncü Yll University Zeve Kampüsü Van 65080 Turkey Department of Physics Engineering Hacettepe University Beytepe Ankara 06800 Turkey

The structural, elastic and electronic properties of YAg-B2（CsCl） were investigated using the first-principles calculations. The energy band structure and the density of states were studied in detail, including partial density of states （PDOS）, in order to identify the character of each band. The structural parameters （lattice constant, bulk modulus, pressure derivative of bulk modulus） and elastic constants were also obtained. The results were consistent with the experimental data available in the literature, as well as other theoretical results.

关键词： YAg electronic band structure density of states elastic constants ab initio rare earths

Synthesis,Crystal and electronic structure of Ba_3ZnSb_2O_9 with the 6H-perovskite-type structure

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Chinese Journal of Structural Chemistry 2012年第1期31卷 73-78页

作者：李夜雨张炜龙杨松林耿磊张浩林晨升何长振程文旦 State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of Sciences Graduate School of the Chinese Academy of Sciences

Crystals of Ba3ZnSb2O9 have been grown by a high-temperature solid-state reaction and characterized by single-crystal X-ray ***3ZnSb2O9 crystallizes in the hexagonal P63/mmc space group with a = 5.8663（4）,c = 14.478（2） ,V = 431.49（8） 3,Z = 2 and R（all data） = *** structure of Ba3ZnSb2O9 consists of pairs of face-sharing Sb2O9 bi-octahedra connected via corners with two single layers of mutually isolated ZnO6 *** Ba2＋ ion is bonded to 12 oxygen *** UV-vis absorption spectrum of the compound has been ***,the calculations of band structure and density of states have also been performed with density functional theory *** obtained results tend to support the experimental data of the absorption spectrum.

关键词： crystal growth crystal structure and symmetry X-ray diffraction electronic band structure

First principles study on the surface- and orientation-dependent electronic structure of a WO_3 nanowire

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Journal of Semiconductors 2013年第6期34卷 5-10页

作者：秦玉香化得燕李晓 School of electronics and Information Engineering Tianjin University

The effects of the surface and orientation of a WOnanowire on the electronic structure are investigated by using first principles calculation based on density functional theory(DFT).The surface of the WO3 nanowire was terminated by a bare or hydrogenated oxygen monolayer or bare WOplane,and the[010]- and[001]-oriented nanowires with different sizes were introduced into the theoretical calculation to further study the dependence of electronic band structure on the wire size and *** calculated results reveal that the surface structure, wire size and orientation have significant effects on the electronic band structure,bandgap,and density of states (DOS) of the *** optimized WOnanowire with different surface structures showed a markedly dissimilar band structure due to the different electronic states near the Fermi level,and the O-terminated[001] WOnanowire with hydrogenation can exhibit a reasonable indirect bandgap of 2.340 eV due to the quantum confinement effect,which is 0.257 eV wider than bulk ***,the bandgap change is also related to the orientation-resulted surface reconstructed structure as well as wire size.

关键词： WO_3 nanowire density functional theory electronic band structure density of states

electronic and Optical Properties of Rock-Salt A1N under High Pressure via First-Principles Analysis

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Communications in Theoretical Physics 2008年第10期50卷 990-994页

作者： ZHANG Wei CHEN Xiang-Rong CAI Ling-Cang GOU Qing-Quan Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China International Centre for Materials Physics Chinese Academy of Sciences Shenyang 110016 China Laboratory for Shock Wave and Detonation Physics Research Institute of Fluid Physics Chinese Academy of Engineering Physics Mianyang 621900 China

electronic and optical properties of rock-salt AIN under high pressure are investigated by first-principlesmethod based on the plane-wave basis *** of band structures suggests that the rock-salt AIN has an indirectgap of 4.53 eV,which is in good agreement with other *** investigating the effects of pressure on the energygap,the different movement of conduction band at X point below and above 22.5 GPa is *** opticalproperties including dielectric function,absorption,reflectivity,and refractive index are also calculated and *** found that the rock-salt AIN is transparent from the partially ultra-violet to the visible light area and hardly does thetransparence affected by the ***,the curve of optical spectrum will shift to high energy area (blueshift) with increasing pressure.

关键词： semiconductors electronic band structure optical properties density functional theory

Pressure-dependent physical properties of cubic SrΒO3(Β=Cr,Fe)perovskites investigated by density functional theory

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Chinese Physics B 2020年第12期29卷 212-220页

作者： Md Zahid Hasan Md Rasheduzzaman Khandaker Monower Hossain Department of Electrical and electronic Engineering International Islamic University ChittagongKumiraChittagong-4318Bangladesh Department of Materials Science and Engineering University of RajshahiRajshahi-6205Bangladesh

We perform the first-principles investigations of the structural,elastic,electronic,and optical properties of SrBO3(B=Cr,Fe)perovskites under pressure based on density functional theory(DFT).This is the first detailed pressure-dependent study of the physical properties for these *** calculated structural parameters are consistent with the existing experimental results and slightly decrease with the application of *** mechanical properties are discussed in detail and reveal that the SrCrO3 is harder than *** pressure,these compounds behave like half-metals,confirmed by their band structure and density of *** the SrCrO3 retains its half-metallic nature under pressure,SrFeO3 becomes metallic for both up-spin and down-spin *** charge density and bond overlap population reveal the covalent nature of Cr–O bond and Fe–O bond in the studied *** optical properties of SrBO3,also discussed for the first time,reveal some interesting results.

关键词： density functional theory(DFT) effects of pressure electronic band structure optical properties

Persistent surface states with diminishing gap in MnBi_(2)Te_(4)/Bi_(2)Te_(3) superlattice antiferromagnetic topological insulator

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Science Bulletin 2020年第24期65卷 2086-2093,M0005页

作者： Lixuan Xu Yuanhao Mao Hongyuan Wang Jiaheng Li Yujie Chen Yunyouyou Xia Yiwei Li Ding Pei Jing Zhang Huijun Zheng Kui Huang Chaofan Zhang Shengtao Cui Aiji Liang Wei Xia Hao Su Sungwon Jung Cephise Cacho Meixiao Wang Gang Li Yong Xu Yanfeng Guo Lexian Yang Zhongkai Liu Yulin Chen Mianheng Jiang Center for Excellence in Superconducting electronics State Key Laboratory of Functional Material for InformaticsShanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China School of Physical Science and Technology ShanghaiTech University and CAS-Shanghai Science Research CenterShanghai 201210China ShanghaiTech Laboratory for Topological Physics Shanghai 200031China University of Chinese Academy of Sciences Beijing 100049China College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China State Key Laboratory of Low Dimensional Quantum Physics Department of PhysicsTsinghua UniversityBeijing 100084China Department of Physics Clarendon LaboratoryUniversity of OxfordOxford 0X13PUUK Advanced Light Source Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA Diamond Light Source Harwell CampusDidcot 0X11 ODEUK Frontier Science Center for Quantum Information Beijing 100084China RIKEN Center for Emergent Matter Science(CEMS) WakoSaitama 351-0198Japan

Magnetic topological quantum materials(TQMs) provide a fertile ground for the emergence of fascinating topological magneto-electric effects. Recently, the discovery of intrinsic antiferromagnetic(AFM) topological insulator MnBi_(2)Te_(4) that could realize quantized anomalous Hall effect and axion insulator phase ignited intensive study on this family of TQM compounds. Here, we investigated the AFM compound Mn Bi4 Te7 where Bi_(2)Te_(3) and MnBi_(2)Te_(4) layers alternate to form a superlattice. Using spatial-and angleresolved photoemission spectroscopy, we identified ubiquitous(albeit termination dependent) topological electronic structures from both Bi_(2)Te_(3) and MnBi_(2)Te_(4) terminations. Unexpectedly, while the bulk bands show strong temperature dependence correlated with the AFM transition, the topological surface states with a diminishing gap show negligible temperature dependence across the AFM *** with the results of its sister compound MnBi_(2)Te_(4), we illustrate important aspects of electronic structures and the effect of magnetic ordering in this family of magnetic TQMs.

关键词： Spatially resolved angle-resolved photoemission spectroscopy electronic band structure Quantum anomalous Hall effect Magnetic topological insulator

Photoreflectance system based on vacuum ultraviolet laser at 177.3 nm

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Chinese Physics B 2022年第11期31卷 100-105页

作者： Wei-Xia Luo Xue-Lu Liu Xiang-Dong Luo Feng Yang Shen-Jin Zhang Qin-Jun Peng Zu-Yan Xu Ping-Heng Tan State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of Sciences(CAS)Beijing 100083China Center of Materials Science and Optoelectronics Engineering&CAS Center of Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100049China Jiangsu Key Laboratory of ASIC Nantong UniversityNantong 226019China Key Laboratory of Solid State Laser Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China Key Laboratory of Function Crystal and Laser Technology Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China

Photoreflectance(PR)spectroscopy is a powerful and non-destructive experimental technique to explore interband transitions of *** most PR systems,the photon energy of the pumping beam is usually chosen to be higher than the bandgap energy of the *** the best of our knowledge,the highest energy of pumping laser in reported PR systems is 5.08 eV(244 nm),not yet in the vacuum ultraviolet(VUV)*** this work,we report the design and construction of a PR system pumped by VUV laser of 7.0 eV(177.3 nm).At the same time,dual-modulated technique is applied and a dual channel lock-in-amplifier is integrated into the system for efficient PR *** system’s performance is verified by the PR spectroscopy measurement of well-studied semiconductors,which testifies its ability to probe critical-point energies of the electronic band in semiconductors from ultraviolet to near-infrared spectral region.

关键词： photoreflectance spectroscopy vacuum ultraviolet laser electronic band structure critical points of electron density of states

Tunable electron and phonon properties of folded single-layer molybdenum disulfide

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Nano Research 2018年第3期11卷 1541-1553页

作者： Jie Peng Peter W. Chung Madan Dubey Raju R. Namburu Department of Mechanical Engineering University of Maryland College Park MD 20742 USA Sensors & Electron Devices Directorate U.S. Army Research Laboratory Adelphi MD 20783 USA Computational & Information Sciences Directorate U.S. Army Research Laboratory Aberdeen Proving Ground MD 21005 USA

A unique feature of transition metal dichalcogenides is their single-layer form, which enables folding. Although folding has been found to significantly affect the photoluminescence spectrum and some in-plane properties, only limited insight has been gained on how to modulate those properties. In this report, we examine the structure of folds of a single sheet of MoS2 and the dependence of the ground-s tate electronic and phonon transport properties on the wrapping length. As the folded structure is effectively a bilayer that terminates in a loop, the wrapping length modulates the relative size of the bilayer region to the closed loop along the edge. A combination of computational methods, including approaches based on variational mechanics, classical potentials, and density functional theory, are employed. Highly accurate calculations of the reference folded structure are first carried out to show that the folded structure is largely insensitive to the wrapping length. The folded structures are subsequently used to estimate the electronic band gap, which is found to vary significantly as a function of the wrapping length, and converges from below to the limit value corresponding to an infinite bilayer. The gap values range from 0.43 to 1.09 eV, with a crossover to an indirect gap, which suggests that the transitions must be lattice-assisted, similar to the transitions in the bilayer and bulk forms. However, the phonons, while affected by the formation of the folded structure, are insensitive to the wrapping length. In fact, the overall thermal transport behavior along the folding axis is unchanged. The possibility of modulating the gap value while keeping the thermal properties unchanged opens up new exciting avenues for further applications of this emerging material.

关键词： molybdenum disulfide folded structure electronic band structure thermal conductivity phonon

Theoretical optoelectronic analysis of intermediate-band photovoltaic material based on ZnY_(1-x) O_x(Y = S,Se,Te) semiconductors by first-principles calculations

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Chinese Physics B 2013年第10期22卷 463-468页

作者：吴孔平顾书林叶建东汤琨朱顺明周孟然黄友锐张荣郑有炓 School of Electrical and Information Engineering Anhui University of Science and Technology Nanjing National Laboratory of Microstructures School of Electronic Science and EngineeringNanjing University Data Storage Institute A*STARSingapore 117608Singapore

The structural, energetic, and electronic properties of lattice highly mismatched ZnY1-xOx （Y = S, Se, Te） ternary alloys with dilute O concentrations are calculated from first principles within the density functional theory. We demonstrate the formation of an isolated intermediate electronic band structure through diluted O-substitute in zinc-blende ZnY （Y = S, Se, Te） at octahedral sites in a semiconductor by the calculations of density of states （DOS）, leading to a significant absorption below the band gap of the parent semiconductor and an enhancement of the optical absorption in the whole energy range of the solar spectrum. It is found that the intermediate band states should be described as a result of the coupling between impurity O 2p states with the conduction band states. Moreover, the intermediate bands （IBs） in ZnTeO show high stabilization with the change of O concentration resulting from the largest electronegativity difference between O and Te compared with in the other ZnSO and ZnSeO.

关键词： intermediate band (IB) electronic band structure optical properties electronegativity