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First-principles calculation of the electronic structure, chemical bonding, and thermodynamic properties of β-US_2

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Chinese Physics B 2015年第12期24卷 470-476页

作者：李世长郑远蕾马生贵高涛敖冰云 Institute of Atomic and Molecular Physics Sichuan University Science and Technology on Surface Physics and Chemistry Laboratory

The electronic structure, magnetic states, chemical bonding, and thermodynamic properties of β-US2 are investigated by using first-principles calculation through the density functional theory（DFT）＋U approach. The obtained band structure exhibits a direct band gap semiconductor at Γ point with a band gap of 0.9 e V for β-US2, which is in good agreement with the recent experimental data. The charge-density differences, the Bader charge analysis, and the Born effective charges suggest that the U–S bonds of the β-US2 have a mixture of covalent and ionic characters, but the ionic character is stronger than covalent character. The Raman-active, infrared-active, and silent modes at the Γ point are further assigned and discussed. The obtained optical-mode frequencies indicate that the three apparent LO–TO（longitudinal optical–transverse optical） splittings occur in B1 u, B2 u, and B3 umodes, respectively. Furthermore, the Helmholtz free energy ？F, the specific heat ？E, vibrational entropy S, and constant volume CVare studied over a range from 0 K-100 K. We expect that our work can provide some valuable information for further experimental investigation of the dielectric properties and the infrared reflectivity spectrum of uranium chalcogenide.

关键词： β-US2 magnetization chemical bonding thermodynamic properties

Effect of sintering temperature on the chemical bonding,electronic structure and electrical transport properties of β-Ga_(1.9)Fe_(0.1)O_(3) compounds

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Journal of Materials Science & Technology 2021年第8期67卷 135-144页

作者： Swadipta Roy C.V.Ramana Center for Advanced Materials Research(CMR) University of Texas at El PasoEl Paso500 W University AveEl PasoTX79968United States

A model system,which is based on iron(Fe)doped gallium oxide(Ga_(2)O_(3))(Ga_(1.9)Fe_(0.1)O_(3)),has been considered to elucidate the combined effect of transition-metal ion doping and processing temperature on the chemistry,local structure and chemical bonding,and electrical transport properties of a wide band gap oxide(Ga_(2)O_(3)).The Ga_(1.9)Fe_(0.1)O_(3) compounds were synthesized using standard high-temperature solid state reaction *** effect of processing conditions in terms of different calcination and sintering environments on the structural and electrical properties of Ga_(1.9)Fe_(0.1)O_(3) compounds is studied in *** characterization by Raman spectroscopy revealed that Ga_(1.9)Fe_(0.1)O_(3) compounds exhibit monoclinic crystal symmetry,which is quite similar to the intrinsic parental crystal structure,though Fedoping induces lattice *** temperature(T_(sint))which was varied in the range of 900-1200℃,has significant impact on the structure,chemical bonding,and electrical properties of Ga_(1.9)Fe_(0.1)O_(3) *** spectroscopic measurements indicate the proper densification of the Ga_(1.9)Fe_(0.1)O_(3) compounds achieved through complete Fe diffusion into the parent Ga_(2)O_(3) lattice which is evident at the highest sintering *** X-ray photoelectron spectroscopy validates the chemical states of the constituent elements in Ga_(1.9)Fe_(0.1)O_(3) *** electrical properties of Ga_(1.9)Fe_(0.1)O_(3) fully controlled by T_(sint),which governed the grain size and microstructural *** temperature and frequency dependent electrical measurements demonstrated the salient features of the Fe doped Ga_(2)O_(3) *** activation energy determined from Arrhenius equation is 0.5 e *** results demonstrate that control over structure,morphology,chemistry and electrical properties of the Ga_(1.9)Fe_(0.1)O_(3) compounds can be achieved by optimizing T_(sint).

关键词： Ga_(2)O_(3)compounds Fe-doping Raman spectroscopy chemical bonding Electrical properties

First principles calculation on electronic structure,chemical bonding,elastic and optical properties of novel tungsten triboride

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Journal of Central South University 2014年第2期21卷 500-505页

作者：王一夫夏庆林余燕 Key Laboratory of High Performance Computing and Stochastic Information Processing of Ministry of Education of China (College of Mathematics and Computer Science Hunan Normal University) School of Physics and Electronics Central South University

The electronic structures,chemical bonding,elastic and optical properties of the novel hP24 phase WB3 were investigated by using density-functional theory(DFT) within generalized gradient approximation(GGA).The calculated energy band structures show that the hP24 phase WB3 is metallic *** density of state(DOS) and the partial density of state(PDOS) calculations show that the DOS near the Fermi level is mainly from the W 5d and B 2p *** analysis suggests that the chemical bonding in hP24-WB3 has predominantly covalent characteristics with mixed covalent-ionic *** physical properties,such as lattice constant,bulk modulus,shear modulus and elastic constants Cij were *** elastic modulus E and Poisson ratio υ were also *** results show that hP24-WB3 phase is mechanically stable and behaves in a brittle *** analysis of all optical functions reveals that WB3 is a better dielectric material,and reflectivity spectra show that WB3 can be promised as good coating material in the energy regions of 8.5-11.4 eV and 14.5-15.5 eV.

关键词： hP24-WB3 first principles calculation electronic structure chemical bonding elastic properties optical properties

Electronic Structures and chemical bonding of NbS6^(-/0)Clusters

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Chinese Journal of Structural Chemistry 2016年第2期35卷 175-184页

作者： WANG Bin LI Qian-Qian WANG Jian-Fu HUANG Xin ZHANG Yong-Fan Department of Chemistry Fuzhou UniversityFuzhou 350116China Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry Xiamen 361005China

Density functional theory（DFT） and coupled cluster theory（CCSD（T）） calculations were employed to investigate the structural and electronic properties of Nb S6^- and Nb S6 clusters. Generalized Koopmans＇ theorem was applied to predict the vertical detachment energies and simulate the photoelectron spectra（PES）. The current study indicated that various types of sulfur ligands（i.e., S^（2-）, S^（2-）, S2^（2-） and S3^（2-）） were presented in the lowest-energy structures of Nb S6^（-/0）. The ground-state structure of Nb S6^- is shown to be Cs（~1A＇） symmetry with a terminal S^（2-）, a side-on bound S2^（2-） and a S3^（2-） ligands. Molecular orbital analyses were performed to analyze the chemical bonding in NbS6^（-/0） clusters and elucidate their structural and electronic properties.

关键词： niobium sulfide cluster density functional theory(DFT) simulated photoelectron spectroscopy chemical bonding

Hybridization： A chemical bonding Nature of Atoms

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Chinese Journal of Chemistry 2017年第9期35卷 1452-1458页

作者： Dongfeng Xue Congting Sun Xiaoyan Chen State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China

Both the bonding mode and geometry can serve as the chemical bonding nature of central cation, which is essentially determined by the atomic orbital-hybridization. In this work, we focus on the possible chemical bonding scheme of central cations on the basis of a quantitative analysis of electron domain of an atom. Starting from the hybridization of outer atomic orbitals that are occupied by valence electrons, we studied the possible orbital hybridization scheme of atoms in the periodic table and the corresponding coordination number as well as possible molecular geometries. According to distinct hybrid orbital sets, the chemical bonding of central cations can be classified into three typical types, resulting in the cations with a variety of coordination numbers ranging from 2 to 16. Owing to different hybridization modes, the highest coordination number of cations in IA and IIA groups is larger than that in IB--VIIIB groups, and the coordination number of lanthanide elements is most abundant. We also selected NaNO3, Fe（NO3）3·9H2O, Zn（NO3）2·6H2O, Y（NO3）3·3H2O, and La（NO3）3·6H2O as examples to confirm the direct relationship between chemical bonding characteristics and orbital hybrid set by IR spectra. The present study opens the door to reveal the chemical bonding nature of atoms on the basis of hybridization and will provide theoretical guides in structural design at an atomic level.

关键词： hybridization chemical bonding coordination number central cations rare earth

Electronic Structure and chemical bonding of a Tetranuclear Neodymium Complex Nd_4O(OR)_4(NR'_2)_6

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Journal of Rare Earths 1993年第2期11卷 93-97页

作者：高松黎乐民徐光宪 Department of Chemistry Peking UniversityBeijing 100871China

The nonrelativistic DV-X_α-SCC method was used to study the electronic structure and chemi- cal bonding of tetranuclear neodymium complex Nd_4O(OR)_4(NR′_2)_6,with emphasis on the bonding charac- ter of the central μ_4-O atom and the four Nd *** results of calculation show that the μ_4-O atom uses its sp^3 valence orbitals to contribute four O-Nd bonding MOs with character of multicenter bond apparent- *** Mulliken population analysis shows that the overlap population between Nd atoms is almost equal to zero,therefore there is no direct metal-metal bond between Nd *** coordination number of Nd in the complex is discussed briefly.

关键词： Rare earth Tetranuclear neodymium complex Electronic structure chemical bonding

chemical bonding and elastic properties of quaternary arsenide oxides YZnAsO and LaZnAsO investigated by first principles

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Transactions of Nonferrous Metals Society of China 2011年第6期21卷 1378-1382页

作者：施毅敏叶绍龙湖南工学院基础教学部衡阳421000 中南大学冶金科学与工程学院长沙410083

The structural parameters, chemical bonding and elastic properties of the tetragonal phase quaternary arsenide oxides YZnAsO and LaZnAsO were investigated by using density-functional theory （DFT） within generalized gradient approximation （GGA）. The GGA calculated structural parameters are in agreement with the experimental results. Population analysis suggests that the chemical bonding in YZnAsO and LaZnAsO can be classified as a mixture of ionic and covalent characteristic. Single-crystal elastic constants were calculated and the polycrystalline elastic modules were estimated according to Voigt, Reuss and Hill＇s approximations （VRH）. The result shows that both YZnAsO and LaZnAsO are relatively soft materials exhibiting ductile behavior. The calculated polycrystalline elastic anisotropy result shows that LaZnAsO is more anisotropy in compressibility and YZnAsO is more anisotropy in shear.

关键词： YZnAsO LaZnAsO chemical bonding elastic properties density-functional theory generalized gradientapproximation Voigt, Reuss and Hill's approximations

First principles study of electronic structure, chemical bonding and elastic properties of BiOCuS

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Transactions of Nonferrous Metals Society of China 2012年第5期22卷 1197-1202页

作者：潘留仙夏庆林叶绍龙丁宁刘自然湖南涉外经济学院电气与信息工程学院长沙410205 中南大学物理与电子学院长沙410083 中南大学冶金科学与工程学院长沙410083

The electronic structures, chemical bonding and elastic properties of the tetragonal phase BiOCuS were investigated by using density-functional theory （DFT） within generalized gradient approximation （GGA）. The calculated energy band structures show that the tetragonal phase BiOCuS is an indirect semiconductor with the calculated band gap of about 0.503 eV. The density of states （DOS） and the partial density of states （PDOS） calculations show that the DOS near the Fermi level is mainly from the Cu-3d state. Population analysis suggests that the chemical bonding in BiOCuS has predominantly ionic character with mixed covalent-ionic character. Basic physical properties, such as lattice constant, bulk modulus, shear modulus, elastic constants, were calculated. The elastic modulus and Poisson ratio were also predicted. The results show that tetragonal phase BiOCuS is mechanically stable and behaves in a ductile manner.

关键词： BiOCuS first principles electronic structures chemical bonding elastic properties

Study on Infrared Spectra and chemical bonding of the Cluster Anion[Cl_2FeS_2MoS_2Cu(PPh_3)_2]￣-

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Chinese Journal of Structural Chemistry 1994年第2期13卷 139-145页

作者：孔宪玲 Lu Yi FujianInstituteofResearchontheStructureofMatter Ch FujianInstituteofResearchonth

The Fourier transform infrared spectra of the cluster anion[Cl2Fe2S2MoS2Cu(PPh3)2]- are measured between 550 and 90 cm(-1).The empirical assignments have been made for the vibration bands of main valence *** order to verify the assignments of the bands and obtain the force constants the approximate normal coordinate analysis for the title anion has been carried *** is found that the calculated frequencies are in good agreement with the observed *** Quantum-chemical calculation is used to elucidate the chemical bonding characteristics for the title anion.

关键词： Mo-Fe-Cu cluster IR spectra chemical bonding force constant