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第一性原理对Ga_nN_n(n=2~5)小团簇的结构及电子性质的研究 总被引:1,自引:0,他引:1
利用密度泛函理论的B3LYP方法在6-31G*的水平上对GanNn(n=2~5)团簇的结构进行优化,得到了GanNn(n=2~5)团簇的最稳定结构.并对最稳定结构的电子性质、成键特性和极化率进行分析.结果表明,团簇的最稳定结构为平面结构,且存在着N2和N3单元,说明N-N键在团簇的形成过程中起着决定性的作用;能隙间隔为1.776~3.563eV,表明GanNn(n=2~5)团簇已具有了半导体的性质. 相似文献
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用密度泛函理论(DFT)中的杂化密度泛函B3LYP方法,在6-31G(d)的水平上对Si6N2团簇的可能结构进行了几何结构优化和电子结构计算,得到了16个可能的异构体.Si6N2团簇的最稳定结构是有4个Si-N键和4个Si-Si键的三维结构.自然键轨道方法分析成键性质的结果表明,Si-N键中Si原子向N原子有较大的电荷转移,因此Si-N原子间有较强的电相互作用;最强的IR和Raman谱峰分别位于1359.14cm-1和1366.29cm-1处;并计算了Si6N2团簇的最稳定结构的极化率和超极化率. 相似文献
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用密度泛函理论(DFT)中的杂化密度泛函B3LYP方法,在6—31G(d)的水平上对Si6N2团簇的可能结构进行了几何结构优化和电子结构计算,得到了16个可能的异构体.Si6N2团簇的最稳定结构是有4个Si-N键和4个Si—Si键的三维结构.自然键轨道方法分析成键性质的结果表明,Si—N键中Si原子向N原子有较大的电荷转移,因此Si-N原子间有较强的电相互作用;最强的IR和Raman谱峰分别位于1359.14cm^-1和1366.29cm^-1处;并计算了Si6N2团簇的最稳定结构的极化率和超极化率. 相似文献
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从头计算对GanNm团簇的结构与稳定性的研究 总被引:2,自引:0,他引:2
用B3LYP-DFT方法对GanN2(n=1~7)和GanN(n=2~8)团簇的结构与稳定性进行了研究.在6-31G*水平上进行了结构优化和频率分析,得到了GanN2(n=1~7)和GanN(n=2~8)团簇的基态结构.在GanN(n=2~8)团簇的基态几何结构中,N原子处在分子结构的中心;在GanN2(n=1~3)团簇中,N—N键比Ga—N键强;在GanN2(n=4~7)团簇中存在Ga3N单元和Ga4N单元.在GanN2(n=1~7)和GanN(n=2~8)团簇中,Ga4N2,Ga6P2,Ga3N,Ga5N和Ga7N较其它团簇稳定. 相似文献
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Ga_nN_3(n=1~8)团簇几何结构及光电子能谱的研究 总被引:2,自引:2,他引:0
用密度泛函理论的B3LYP方法在6-31G*的水平上,对GanN3(n=1~8)团簇的结构进行优化,并对体系的成键特性、光电子能谱及稳定性进行了计算与分析,得到了GanN3(n=1~8)团簇的最稳定结构.结果表明,当n≤5时,其基态几何结构为平面结构,N-N键在这些团簇的形成过程中起着决定性的作用;当n≥6时,其基态几何结构为立体结构,Ga-N键起主导作用;在所研究的团簇中,Ga4N3、Ga7N3的基态结构最稳定;随着n值的增大,平均极化率逐渐增强;通过对光电子能谱的分析,得到Ga-N键的振动频率与六方晶系纤锌矿结构GaN的光学声子峰值相近. 相似文献
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用密度泛函理论(DFT)中的杂化密度泛函B3LYP方法,在6-31G(d)的水平上对Si4N4团簇的可能结构进行了几何结构优化和电子结构计算,得到了可能的17个异构体.Si4N4团簇的最稳定结构是有8个Si-N键的平面结构.用自然键轨道(NBO)方法分析了成键性质.计算结果表明,Si-N键中Si原子向N原子有较大的电荷转移,因此Si-N原子间有较强的电相互作用;最强的IR和Raman谱峰分别位于1387.64cm-1和1415.05cm-1处;并计算了Si4N4团簇的最稳定结构的极化率和超极化率. 相似文献
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利用密度泛函理论,在B3LYP/6-31+G(d, p)基组水平上对苯酚-水团簇C_6H_5OH(H_2O)_n(n=1-6)的可能构型进行全优化,得到了团簇的稳定结构;在B3LYP/6-311++G(d, p)基组水平上计算得到了各团簇构型的总能量和结合能,结果显示,在团簇尺寸较小(n≤5)时,团簇C_6H_5OH(H_2O)_n的最稳定结构为平面的环状结构,团簇尺寸较大(n5)时,团簇C_6H_5OH(H_2O)_n的最稳定结构为三维立体结构.通过对团簇结合能的二阶差分、最高占据轨道与最低空轨道之间的能隙、费米能级和电离能的分析发现,团簇C_6H_5OH(H_2O)_2的最低能量结构具有较高的稳定性,可能具有幻数结构. 相似文献
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O. Moze J.M. Cadogan Y. Janssen F.R. de Boer K.H.J. Buschow S.J. Kennedy 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(1):29-36
The magnetic structure of RFe6Ga6 intermetallic compounds with R = Y, Ho have been determined by neutron powder diffraction, 57Fe M?ssbauer spectroscopy, AC susceptibility, TGA (Thermo-Gravimetric Analysis) and magnetization measurements. Both compounds
crystallize in the tetragonal ThMn12 structure (space group I4/mmm) with the magnetic structure of YFe6Ga6 consisting of a simple ferromagnetic alignment of Fe moments in the basal plane with a Curie temperature of 475(5) K. Gallium
atoms are found to fully occupy the 8i site, with Fe and Ga atoms equally distributed over the 8j site, whilst Fe atoms fully
occupy the 8f site. The average Fe moments are 1.68(10)
and 1.46(10)
at 15 and 293 K, respectively. The average room temperature Fe magnetic moments determined by neutron diffraction are in
overall agreement with the average Fe moment deduced from M?ssbauer spectroscopy and bulk magnetization measurements on this
compound. The magnetic anisotropy of the compound HoFe6Ga6 is also planar in the temperature range 6-290 K, with Ho magnetic moments of 9.28(20)
and 2.50(20)
at 6 K and 290 K, respectively, coupled anti-ferromagnetically to the Fe sublattice and a Curie temperature of 460(10) K.
The magneto-crystalline anisotropies of both compounds are comparable at low temperatures.
Received 8 March 2001 and Received in final form 18 June 2001 相似文献
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CARS spectra of thev
1-band of SF6 and UF6 performed under (static) cell conditions and under supersonic jet expansion have been recorded. The cooling behavior in supersonic jet expansions has been demonstrated for both gases.Work supported by BMFT-funds 相似文献
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D. G. Fleming D. J. Arseneau J. Pan M. Y. Shelley M. Senba P. W. Percival 《Applied magnetic resonance》1997,13(1-2):181-194
Muon spin rotation (μSR) and avoided level crossing resonance (ALCR) have been used to determine the hyperfine coupling constants (hfcs) of the muonium-substituted cyclohexadienyl radicals C6H6Mu, C6D6Mu and C6F6Mu in the gas phase, at pressures ~1 and 15 atm and temperatures in the range 40–80°C. Equivalent studies of polyatomic free radicals in gases, by electron spin resonance (ESR) spectroscopy, are generally not possible in this pressure range. The present gas phase results support the findings of earlier studies of cyclohexadienyl radicals in the condensed phase, by both μSR and ESR. Minor but not insignificant (~1%) effects on the hfcs are observed, which can be qualitatively understood for such nonpolar media in terms of their differing polarizabilities. This is the first time that comparisons of this nature have been possible between different phases at the same temperatures. These μSR/ALCR gas-phase results provide a valuable benchmark for computational studies on radicals, free from possible effects of solvent or matrix environments. 相似文献
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《中国科学:物理学 力学 天文学(英文版)》2017,(1)
<正>In last decades,topological materials[1-3]have attracted lots of research interest.Topological Kondo insulator(TKI)[4],as an exotic quantum state,has been proposed theoretically in two hexaborides Sm B6and Yb B6,in which there is a d/f(p)band inversion at momentum point X[5].There are lots of experimental work supporting the TKI state and metallic surface state in typical Kondo insulator Sm B6[6-10].However,more and more experimental results demonstrated that Yb B6is trivial insulator at ambient pressure[11].Under high pressure,the band gap of Yb B6will close and the d/p band inversion can happen under pressure about 15 GPa[12]. 相似文献
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J. Lotrian Y. Guern J. Cariou A. Johannin-Gilles 《Journal of Quantitative Spectroscopy & Radiative Transfer》1979,21(2):143-146
Branching ratio measurements have been performed for all of the observed transitions from eight levels in neutral lead (6p2→6p6d, 6p2→ 6p7s, 6p2→6p8s) excited in a hollow cathode discharge in the 200–730 nm spectral range. From the relative emission intensity data, a set of absolute transition probabilities is derived for 28 lines, including lines for which transition probabilities have not been previously published. The absolute scales are obtained by averaging the measured lifetimes of the 3P01,2, 1P10(6p7s), 3F02,3, 3D01,2(6p6d) levels. 相似文献
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SF_6气体及其衍生物的红外光谱分析 总被引:2,自引:0,他引:2
SF6气体大量应用于气体绝缘组合电器(GIS)中。通过化学方法检测SF6气体及其衍生物是检测GIS设备故障的一种重要方法。该文采用红外光谱技术分析了三种情况下的GIS设备内SF6气体组成情况,得出S2F10气体含量可以用来分析GIS故障原因是否为强火花或者电弧放电引起;CF4气体可以用来表征GIS设备内绝缘气体的绝缘状态。另外,研究表明,GIS设备在线运行时,绝缘气体气室密封失效、造成气体泄漏,引入新的气体杂质的问题比较严重。所以在进行GIS设备维护工作时,绝缘气室的密封维护工作十分重要。文章在研究GIS设备绝缘气体SF6红外谱图的基础之上提出了建立基于红外光谱技术的GIS设备故障诊断专家系统的意见。 相似文献
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Abstract With a simplified dynamical model for molecular packing analysis, crystal and molecular structures of benzene C6H6 and hexachlorobenzene C6H6 were investigated. This model includes thermal motion and molecular deformation effects. Several crystalline structures have been found by the calculation. They are compared to experimental structures determined at various temperatures and pressures, by X-ray diffraction or neutron scattering. A schematic (p, T) phase diagram is suggested for each compound. 相似文献
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A comprehensive set of spectra for the benzene cation and the perdeuterated benzene cation has been recorded with full rotational resolution using zero kinetic energy photoelectron spectroscopy (ZEKE) at high resolution (up to 0.2 cm?1), using a slow-rising extraction pulse. With different rovibronic levels in the S1 6l state as intermediate resonance, the rotational transitions to the vibronic ground state of the cation have been recorded using two-colour, two-photon resonance enhanced multiphoton ionization. A simple spectator model has been employed to simulate the intensities of the ZEKE transitions. By fitting the simulations to the recorded spectra, improved values for the rotational constants and the Coriolis coupling parameters of benzene and perdeuterated benzene have been obtained. The CC and CH bond lengths of the cation have been deduced. The spectator model is shown to be reliable despite the fact that no specific allowance is made for the effect of final state interactions on the signal intensity. 相似文献
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The electron-phonon relaxation times of the crystal-field levels of the metastable state5D4 of Tb3+ were measured between 2 and 4.2K. The relaxation of the lowest pseudodoublet (E=1.25 cm–1) shows an Orbach process via higher crystal-field levels. The other levels show direct relaxation on a nanosecond time scale. The higher crystal-field levels were used to look for propagation of high-energy (4THz) nonequilibrium phonons by phonon-induced fluorescence. No ballistic propagation of high-energy phonons could be found. 相似文献