First-principles calculations of structural and electronic properties of Tl_xGa_(1-x)As alloys

The zincblende ternary alloys Tl_xGa_（1-x） As（0 〈 x 〈 1） are studied by numerical analysis based on the plane wave pseudopotential method within the density functional theory and the local density approximation. To model the alloys,16-atom supercells with the 2 × 2 × 2 dimensions are used and the dependency of the lattice parameter, bulk modulus,electronic structure, energy band gap, and optical bowing on the concentration x are analyzed. The results indicate that the ternary Tl_xGa_（1-x） As alloys have an average band gap bowing parameter of 4.48 eV for semiconductor alloys and 2.412 eV for semimetals. It is found that the band gap bowing strongly depends on composition and alloying a small Tl content with GaAs produces important modifications in the band structures of the alloys.

Structural Phase Transitions of ZnTe under High Pressure Using Experiments and Calculations

The pressure-induced structural transitions of ZnTe are investigated at pressures up to 59.2 GPa in a diamond anvil cell by using synchrotron powder x-ray diffraction method. A phase transition from the initial zinc blende （ZB, ZnTe-Ⅰ） structure to a cinnabar phase （ZnTe-Ⅱ） is observed at 9.6 GPa, followed by a high pressure orthorhombic phase （ZnTe-Ⅲ） with Cmcm symmetry at 12.1 GPa. The ZB, cinnabar （space group P3121）, Cmcm, P31 and rock salt structures of ZnTe are investigated by using density functional theory calculations. Based on the experiments and calculations, the ZnTe-Ⅱ phase is determined to have a cinnabar structure rather than a P3 1 symmetry.

Theoretical calculations of structural, electronic, and elastic properties of CdSe_(1-x)Te_x:A first principles study

The plane wave pseudo-potential method was used to investigate the structural, electronic, and elastic properties of Cd Se_（1-x）Te_x in the zinc blende phase. It is observed that the electronic properties are improved considerably by using LDA ＋ U as compared to the LDA approach. The calculated lattice constants and bulk moduli are also comparable to the experimental results. The cohesive energies for pure Cd Se and Cd Te binary and their mixed alloys are calculated. The second-order elastic constants are also calculated by the Lagrangian theory of elasticity. The elastic properties show that the studied material has a ductile nature.

Application Strategy of Composite Steel Composite Beams in Bridge Design

The combined prefabricated steel-hybrid stacked girder structure is very common in modern bridge design.An actual bridge engineering design project is taken as an example in this paper to analyze the application strategy of this structure,encompassing overall design strategy,structural design strategy,and structural calculation strategy.The aim is to offer insights that can enhance the quality of bridge design.

Structural, magnetic properties, and electronic structure of hexagonal FeCoSn compound

The structural, magnetic properties, and electronic structures of hexagonal Fe Co Sn compounds with as-annealed bulk and ribbon states were investigated by x-ray powder diffraction（XRD）, differential scanning calorimetry（DSC）, transmission electron microscope（TEM）, scanning electron microscope（SEM）, magnetic measurements, and first-principles calculations. Results indicate that both states of FeCoSn show an Ni_2In-type hexagonal structure with a small amount of FeCo-rich secondary phase. The Curie temperatures are located at 257 K and 229 K, respectively. The corresponding magnetizations are 2.57 μB/f.u. and 2.94 μB/f.u. at 5 K with a field of 50 kOe（1 Oe = 79.5775 A·m^（-1））. The orbital hybridizations between 3 d elements are analyzed from the distribution of density of states（DOS）, showing that Fe atoms carry the main magnetic moments and determine the electronic structure around Fermi level. A peak of DOS at Fermi level accounts for the presence of the FeCo-rich secondary phase. The Ni_2In-type hexagonal FeCoSn compound can be used during the isostructural alloying for tuning phase transitions.

QUANTUM CHEMICAL CALCULATIONS ON THE ELECTRONIC STRUCTURE AND SPECTRA OF[Mo_3O_4-nSn]^(4+)(n=O-4)CLUSTER CATIONS

The electronic structure and spectra of [Mo3O4-nSn]^(4+)(n=0-4) cations were calculated by means of INDO/CI quantum chemistry method to account for the experimental data of their spectra in water solutions.

Electronic Structure and Optical Properties in Uranium Dioxide:the First Principle Calculations

We report a study of the electronic structure and optical properties of uranium dioxide （U02） based on the ab-initio density-functional theory and using the generalized gradient approximation. To correctly describe the strong correlation between 5 f electrons of a uranium atom, we employ the on-site Hubbard U correction term and optimize the correlation parameter of the bulk uranium dioxide. Then we give the structural and electronic properties of the ground state of uranium dioxide. Based on the accurate electronic structure, we calculate the complex dielectric function of UO2 and the related optieM properties, such as reflectivity, refractive index, extinction index, energy loss spectra, and absorption coefficient.

Synthesis,Crystal Structure and Band Structure of Sm_3In_5

A new intermetallic compound, Sm3In5, has been synthesized by solid-state reaction of the corresponding pure elements in a welded niobium tube at high temperature. Its crystal structure was established by single-crystal X-ray diffraction. Sm3In5 crystallizes in orthorhombic, space group Cmcm with a = 10.0137（8）, b = 8.1211（7）, c = 10.3858（8） A, V = 844.60（1） A^3, Z = 4, Mr = 1025.15, Dc = 8.062 g/cm^3, μ = 33.791 mm^-1, F（000） = 1724, the final R = 0.0346 and wR = 0.0775 for 533 observed reflections with I 〉 2σ（I）. The structure of Sm3In5 belongs to the modified Pu3Pd5 type. It is isostructural with La3In5 and β-Y3In5, containing one-dimensional （1D） [In5] cluster chains along the c-axis, which are weakly interconnected via In-In bonds （3.345A） to form a three-dimensional （3D） structure. The samarium cations are located at the voids between the 1D [In5] cluster chains. Band structure calculations based on Density Function Theory （DFT） method indicate that Sm3In5 is metallic.

Synthesis and Crystal and Band Structures of YbCu_6In_6 with 3D Framework

A new intermetallic compound,YbCu6In6,has been synthesized by solid-state reaction of the corresponding pure elements in a welded tantalum tube at high temperature.Its crystal structure was established by single-crystal X-ray diffraction.YbCu6In6 crystallizes in tetragonal space group I4/mmm with a = 9.2283（5）,c = 5.4015（4）,V = 460.00（5） 3,Z = 2,Mr = 1243.20,Dc = 8.976 g/cm3,μ = 38.243 mm-1,F（000） = 1076,and the final R = 0.0258 and wR = 0.0602 for 173 observed reflections with I 〉 2σ（I）.The structure of YbCu6In6 belongs to the ThMn12 type.It is isostructural with RECu6In6（RE = Y,Ce,Pr,Nd,Gd,Tb,Dy）,containing one-dimensional（1D） [Cu10In6] cluster chain along the c axis,which is interconnected via sharing the Cu（1） atoms to form a three-dimensional（3D） [Cu6In6] framework with Yb atoms encapsulated in the 1D tunnels along the c axis.Band structure calculations based on Density Functional Theory（DFT） method indicate that YbCu6In6 is metallic.

Synthesis,Crystal Structure and Band Structure of Tb_3Co_4Sn_(13)

A new intermetallic compound,Tb3Co4Sn13,has been synthesized by solid-state reaction of the corresponding pure elements in a welded tantalum tube at high temperature.Its crystal structure was established by single-crystal X-ray diffraction.Tb3Co4Sn13 crystallizes in cubic,space group Pm3n（No.223） with a = 9.5072（2） ,V = 859.33（3） 3,Z = 2,Mr = 2255.45,Dc = 8.717 g/cm3,μ = 34.369 mm-1,F（000） = 1906,and the final R = 0.0140 and wR = 0.0312 for 199 observed reflections with I〉 2σ（I）.The structure of Tb3Co4Sn13 belongs to the Yb3Rh4Sn13 type.It is isostructural with RE3Co4Sn13（RE = La,Ce）,featuring a 3D [Co4Sn12] framework based on [CoSn6] trigonal prisms.The [CoSn6] trigonal prisms are interconnected via corner-sharing and Sn-Sn bonds to form a 3D [Co4Sn12] framework.The other Sn and Tb atoms are located in the spacers of the 3D framework.Band structure calculations indicate that Tb3Co4Sn13 is metallic.

Synthesis,Crystal Structure,DFT Studies and Biological Activity of a Novel Schiff Base Containing Triazolo[4,3-a]pyridine Moiety

The novel Schiff base（E）-8-chloro-NA-（4-（dimethylamino）benzylidene）-[1,2,4]triazolo[4,3-a]pyridine-3-carbohydrazide was synthesized and characterized by ^1H NMR,MS,elemental analysis and X-ray diffraction.The compound crystallizes in the monoclinic space group P2_1/c with a = 7.091（2）,b = 10.750（3）,c = 21.380（6） A,β = 96.299（6）°,V = 1619.7（8） A^3,Z = 4 and R = 0.0351.Theoretical calculation of the title compound was carried out with the B3LYP/6-31 G basis set.The frontier orbital energy and atomic net charges were discussed.It is found that the experimental data show good agreement with the calculated values.And the compound exhibits good antifungal activity against Stemphylium lycopersici（Enjoji） Yamamoto.

Ba_2SbGaS_5 : Solid-state Synthesis, Crystal and Electronic Structures, and Property Characterization

Single crystal of Ba2SbGaSs has been synthesized by the high temperature solidstate reaction method. The compound crystallizes in the orthorhombic space group Pnma with a = 12.177（4）, b = 8.880（3）, c = 8.982（3） A, V= 971.4（6） A3, Z = 4, De = 4.284 g/cm3,μ = 14.487 mm-1, F（000） - 1096, the final R = 0.0171 and wR = 0.0384 for all data. The structure comprises an infinite one-dimensional 1∞[SbGaS5]4- anionic chain constructed from the GaS4 tetrahedra and the SbS5 polyhedra via sharing edge alternately. The paralleled 1∞[SbGaS5]4anionic chains engage with each other and form the two-dimensional Sb-Ga-S layer perpendicular to a-axis with the isolated Ba2＋ cations arranged between layers. The IR spectrum and the UV-Vis spectrum have been investigated. Also, the first-principles band structure and density of states calculations indicate that the compound belongs to indirect semiconductor with the band gap of 2.1 eV, which is supported by the UV-Vis diffuse reflectance results.

Synthesis,Crystal Structure,DFT Studies and Antifungal Activity of 5-(4-Cyclopropyl-5-((3-fluorobenzyl)sulfonyl)-4H-1,2,4-triazol-3-yl)-4-methyl-1,2,3-thiadiazole

5-（4-Cyclopropyl-5-（（3-fluorobenzyl）sulfonyl）-4H-1,2,4-triazol-3-yl）-4-methyl-1,2,3-thiadiazole was synthesized and recrystallized from Et OH. The compound was characterized by ^1H NMR,MS,elemental analysis and X-ray diffraction. The structure-active relationship and the antifungal activity based on density functional theory calculation（DFT） and antifungal activities were investigated. The compound crystallizes in the monoclinic space group P121/n1 with a = 8.929（3）,b=12.715（4）,c=15.161（5） A°,β = 106.142（3）o,V = 1653.3（9） A°3,Z = 4 and R = 0.0393 for 3930 observed reflections with I 〉 2σ（I）. Theoretical calculation of the title compound was carried out with B3LYP/6-31G（d,p）. The full geometry optimization was carried out using the 6-31G（d,p） basis set.The frontier orbital energy and atomic net charges were discussed. The observed results of the compound have been compared with theoretical results and the experimental data show good agreement with the calculated values. The compound exhibits good antifungal activity.

Synthesis,Crystal Structure,and Optical Property of Zero-dimensional Quaternary Thioborate：Ba9B3GaS15

A new zero-dimensional（0D） thioborate Ba_9B_3GaS_（15） has been discovered by conventional high-temperature solid-state reaction. The compound crystallizes in orthorhombic space group Pbca with a = 8.4759（8）,b = 22.266（2）,c = 31.426（3） ？,V = 5931（2） ？~3,Z = 8,Mr = 1819.11,Dc = 4.075 g/cm3,μ = 13.684 mm^（-1）,F（000） = 6320,S = 1.034,（Δρ）max = 5.039,（Δρ）min = –5.409 e/？~3,the final R = 0.0362 and w R = 0.1053 for 19243 observed reflections with I 〉 2σ（I）. The structure is constructed by discrete [BS_3]^（3–） trigonal planes and isolated [GaS_4]^（5–） tetrahedra with Ba^（2＋） and isolated S^（2–） filled among them. The UV-Vis-near-IR spectrum reveals a wide band gap of 3.15 eV that agrees with the electronic structure calculation.

Elastic properties and electronic structures of lanthanide hexaborides

The structural, elastic, and electronic properties of a series of lanthanide hexaborides（Ln B6） have been investigated by performing ab initio calculations based on the density functional theory using the Vienna ab initio simulation package.The calculated lattice and elastic constants of Ln B6 are in good agreement with the available experimental data and other theoretical results. The polycrystalline Young＇s modulus, shear modulus, the ratio of bulk to shear modulus B/G, Poisson＇s ratios, Zener anisotropy factors, as well as the Debye temperature are calculated, and all of the properties display some regularity with increasing atomic number of lanthanide atoms, whereas anomalies are observed for Eu B6 and Yb B6. In addition, detailed electronic structure calculations are carried out to shed light on the peculiar elastic properties of Ln B6.The total density of states demonstrates the existence of a pseudogap and indicates lower structure stability of Eu B6 and Yb B6 compared with others.

Synthesis,Crystal Structure and Photoluminescence of a TADF Cuprous Complex

A cuprous mononuclear copper complex [Cu（adpypz）CH3CNPPh3]BF4·CH2Cl2（1, adpypz = 9,9-dimethyl-10-（6-（3-phenyl-1H-pyrazol-1-yl）pyridin-2-yl）-9,10-dihydroacridine） was synthesized and characterized by Elemental Analysis, NMR, UV-Vis and X-ray single-crystal structure analysis. It crystallizes in triclinic, space group P1 with a = 11.3388（4）, b = 13.4569（4）, c = 16.2561（6） ？, α = 97.154（3）, β = 92.187（3）, γ = 114.119（4）°, V = 2235.38（13） ？3, Z = 2, Mr = 967.12, Dc = 1.437 g/cm^3, F（000） = 996, μ = 2.62 mm^–1, GOOF = 1.031, the final R = 0.0417, and w R = 0.1024 for 8043 observed reflections with I 〉 2σ（I）. The Cu（I） atoms in the complex are four-coordinated and adopt a tetrahedral coordination geometry. In the solid state, the complex exhibits bluish-green photoluminescence with emission peaks λmax = 492 nm（1）, lifetimes 235 μs and quantum yields（ф = 0.279） at room temperature. The studies of varied temperature emission spectra and decay behaviours of the complex indicate that the complex displays thermally activated delayed fluorescence（TADF） at room temperature. The results of the experimental and DFT calculations suggest that the emission in the solid state originates from the ILCT excited states.

Multiscale simulations in face-centered cubic metals:A method coupling quantum mechanics and molecular mechanics

An effective multiscale simulation which concurrently couples the quantum-mechanical and molecular-mechanical calculations based on the position continuity of atoms is presented.By an iterative procedure,the structure of the dislocation core in face-centered cubic metal is obtained by first-principles calculation and the long-range stress is released by molecular dynamics relaxation.Compared to earlier multiscale methods,the present work couples the long-range strain to the local displacements of the dislocation core in a simpler way with the same accuracy.

Surface for methane combustion:O(^3P)+CH4→OH+CH3

Kinetic investigations including quasi-classical trajectory and canonical unified statistical theory method calculations are carried out on a potential energy surface for the hydrogen-abstraction reaction from methane by atom O(^3P).The surface is constructed using a modified Shepard interpolation method.The ab initio calculations are performed at the CCSD(T)level.Taking account of the contribution of inner core electrons to electronic correlation interaction in ab initio electronic structure calculations,modified optimized aug-cc-pCVQZ basis sets are applied to the all-electrons calculations.On this potential energy surface,the triplet oxygen atom attacks methane in a near-collinear H-CH3 direction to form a saddle point with barrier height of 13.55 kcal/mol,which plays a key role in the kinetics of the title reaction.For the temperature range of 298-2500 K,our calculated thermal rate constants for the O(^3P)+CH4→OH+CH3 reaction show good agreement with relevant experimental data.This work provides detailed mechanism of this gas-phase reaction and a theoretical guidance for methane combustion.

Investigation of Performance of Turret Assembly in Inboard Turret Mooring System

To fulfil the need of development of offshore oil floating production system, the performance of turret assembly in an inboard turret mooring system has been investigated in the paper. By means of systematic evaluation, the optimal structure of the turret for single-point mooring systems has been determined. Through model tests of a turret mooring system, several groups of data such as forces, moments and displacements under different environmental conditions have been obtained. Stresses and strains of the turret structure have been calculated by means of the finite element method corresponding to the situation in the model experiment. The study shows that the selected turret structure and the designed turret assembly are technically feasible.

Synthesis, Crystal Structure and Band Structure of EuMg_6Sn_(3.67)

EuMg6Sn3.67 has been synthesized by reacting the mixture of the corresponding pure elements at high temperature, and structurally characterized by single-crystal X-ray diffraction study. EuMg6Sn3.67 crystallizes in hexagonal space group P63/m （No. 176） with a = 11.7259（4）, c = 4.5507（2） A, V= 541.88（4）A3 Z = 2, Mr = 734.60, Dc= 4.502 g/cm3, μ = 14.348 mm-1, F（000） = 638, the final R = 0.0128 and wR = 0.0378 for 464 observed reflections with 1 〉 2σ-（1）. EuMg6Sn3.67 is closely related to the Ba2Mg2GeT.33 structure type and features a three-dimensional [Mg6Sn3.67] framework with one-dimensional hexagonal tunnels along the c-axis occupied by the Eu atoms. Electronic structure calculation indicates that the title compound is metallic.