共查询到19条相似文献,搜索用时 171 毫秒
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采用密度泛函理论和非平衡格林函数相结合的方法研究了S原子作为单、双端基的(CH3)2-OPE (齐聚苯乙炔)和(NH2)2-OPE分子在金电极间的电子输运性质. 通过第一性原理优化计算获得分子部分稳定结构, 再置于Au电极之间构成两极系统, 然后再优化整个两极系统获得稳定结构. 另外, 通过非平衡格林函数方法计算了两极系统的电子输运性质. 计算结果表明, 不同的修饰基团和桥接方式可以导致两极系统的开关效应、负微分电阻行为和整流行为等不同的电子输运性质. 通过计算不同偏压下的分子体系投影轨道电子分布、透射谱、态密度, 对这些新异的电输运性质出现的机理进行了解释. 相似文献
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用密度泛函理论的杂化密度泛函B3LYP方法在6-31G*基组水平上对[Mg(NH2)2]n(n=1—5)团簇各种可能的构型进行几何结构优化,预测了各团簇的最稳定结构.对最稳定结构的振动特性、成键特性、电荷特性等进行了理论研究.结果表明:团簇易形成链状结构,Mg—N键长为0.190—0.234 nm,N—H键长为0.101—0.103 nm,H—N—H键角为100.2°—107.5°;团簇中M
关键词:
2)2]n(n=1—5)团簇')" href="#">[Mg(NH2)2]n(n=1—5)团簇
密度泛函理论
结构与性质
储氢材料 相似文献
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对于RGB有机电致发光器件(OLEDs),蓝光非常重要.在现有各种蓝光材料中,聚芴(PFO)非常稳定且荧光量子效率可达80%,但它有一个非常大的缺点:电致发光会产生异常绿光带.这严重影响了PFO相关器件的饱和色纯度.本文使用分子基磁性材料Fe(NH2trz)3·(BF4)2掺杂PFO方法,解决了这一难题.以ITO为衬底,制作了结构为ITO/PEDOT:PSS/PFO:Fe(NH2trz)3·(BF4)2/CsCl/Al的器件.报道了利用Fe(NH2trz)3·(BF4)2特殊的电子自旋态调制PFO的光电特性,实现了PFO的强烈纯正蓝光发射.详细研究了Fe(NH2trz)3·(BF4)2对PFO光电特性的影响.在4 V至9 V电压的偏置下,没有Fe(NH2trz)3·(BF4)2的器件,发出特别异常的绿光.然而,与此形成明显对照的是:Fe(NH2trz)3·(BF4)2掺杂的器件发出强烈的本征蓝光;PFO绿色发光带被成功压制;随着电压的变化,器件光谱的蓝光部分在整个EL谱所占比例没有改变.运用光电磁一体化测量技术,进一步研究了PFO掺杂Fe(NH2trz)3·(BF4)2器件的磁发光(MEL)和磁电导(MC)效应.发现PFO:Fe(NH2trz)3·(BF4)2和纯PFO薄膜内都没有激基缔合物产生.运用发光动力学理论,分析了Fe(NH2trz)3·(BF4)2阻断PFO异常绿光发射的机理. 相似文献
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运用激光拉曼光谱实验和密度泛函理论计算研究了450~1 700 cm-1光谱范围内有机-无机杂化钙钛矿材料(C6H5CH2NH3)2PbBr4的振动模式特性。对比实验所得拉曼光谱和理论计算所得拉曼光谱,发现密度泛函理论计算可以很好的模拟(C6H5CH2NH3)2PbBr4有机部分的分子振动模式。同时通过比较分析密度泛函理论计算和参考文献,对450~1 700 cm-1光谱范围内的拉曼峰的分子振动模式进行了初步的归属,并发现该光谱范围内的拉曼峰主要是由(C6H5CH2NH3)2PbBr4分子中有机部分振动所产生的。 相似文献
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用分步激发方法及偏振光技术,测定了锶的(5p3/2ns)1(n=13-21)及(5p3/2 nd)3(n=13-24)各自电离谱,在低于5p1/2电离限的(5p3/2ns)1态的实电子激发谱中,出现对应于(5p1/2ns)1及(5p1/2nd)1的畸变峰,畸变峰也出现于(5p3/2nd)3的实电子激发谱中。这说明(5pjns)(5pjnd)自电离系列间存在相互作用。
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本文用X射线粉末法测定了Li2K(IO3)3与Li2NH4(IO3)3的晶体结构和原子参数。发现Li3K(IO3)3,Li2NH4(IO3)3与Li2Rb(IO3)3同晶型,属单斜晶系,空间群为P21/α,每个单胞含有四个化合式量。室温的点阵常数分别为α=11.198?,b=11.046?,c=8.254?,β=111.53°,及α=11.327?,b=11.078?,c=8.341?,β=111.87°。讨论了二元化合物的形成与离子半径的关系。
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The magnetic susceptibility of the layered compounds (CH2)3(NH3)2FeCl2Br2 and (CH2)6(NH3)2FeCl2Br2 has been measured in the range 80 < T < 300 K. The results follow a Curie-Weiss behavior in the range 120 < T < 300 K but are field dependent for T < 120 K. The results are interpreted in terms of a two-dimensional antiferromagnetic interaction which is canted. A comparison with the corresponding pure chloride compounds is given. 相似文献
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The K absorption-edge spectra of the ligand chlorine ion in square-planar complex compounds cis- and trans-[Pt(NH3)2Cl2], trans-[Pd(NH3)2Cl2], and (NH4)2PdCl4 are reported and discussed in connection with the chlorine K absorption spectra of K2PtCl4 and K2PdCl4, reported previously. The observed chemical shift of a white line at the absorption threshold is interpreted in terms of the difference of the ligand-field splitting of electronic states for metal ions. The white line is attributed to the electronic transition from the Cl? ls level to the lowest unoccupied antibonding molecular orbital (MO), which is specified by a in the square-planar complex with D4h symmetry. The other absorption structures are regarded as continuum “shape resonances” of the outgoing electron trapped by the cage of the surrounding atoms. The effect of geometrical isomerism is found in the chlorine K absorption spectra of cis- and trans-[Pt(NH3)2Cl2]. 相似文献
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Z.C. Xia Y. Wang H.R. Zeng Q.X. Zhou M.T. Hu B. Dong G. Liu X.N. Feng L. Liu S.L. Yuan C.Q. Tang 《Solid State Communications》2006,137(4):216-220
The electrical transport and magnetic properties of high Bi doped (La0.73Bi0.27)0.67Ca0.33MnO3 are studied at the temperature and magnetic field ranges from 10 to 300 K and 0 to 3 T. Significant temperature and magnetic field hystereses are observed in both resistivity and magnetization measurements. Meanwhile, an enhanced magnetoresistance effect, within a wide temperature window, is obtained in the (La0.73Bi0.27)0.67Ca0.33MnO3. The hysteresis and enhanced magnetoresistance are discussed based on an inhomogeneous metastable structure related to the Bi dopant. 相似文献
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The transverse magnetoresistance of (TMTSF)2 ClO4 has been investigated in magnetic fields up to 32 T at several temperatures down to 4.2 K and different angles between B and the crystalline axis. Shubnikov-de-Haas oscillations are observed directly on the magnetoresistance at fields higher than 10 T giving a fundamental field of 259± 10 T in a direction close to c1 axis. 相似文献
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The linear birefringence (LB) of the antiferromagnet (CH2)2(ND3)2MnCl4 has been measured as a function of temperature and in magnetic fields up to 100 kOe. The temperature dependence of the LB points to a pronounced two dimensional magnetic behaviour. No anomaly corresponding to the effect of three dimensional ordering could be detected at TN. In theffield dependent measurements the spin flop at HSF = 33.6 ± 1 kOe (T = 4K) could clearly be detected. 相似文献
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I. Heilmann J.M. Knudsen N.B. Olsen B. Buras J. Staun Olsen 《Solid State Communications》1974,15(9):1481-1484
Thermal decomposition products of the Mohr salt (NH4)2Fe(SO4)2·6H2O have been studied and identified using the Mössbauer effect, X-ray diffraction, infrared spectroscopy, and the gravimetric and thermal differential methods. It has been found that the Mohr salt heated for 96 hr. in air at 520K changes to a single substance identified as NH4Fe(SO4)2 with a single Mössbauer line (width 0.30 mm/sec; isomeric shift 0.30 mm/sec). When the Mohr salt is heated for 1 hr. in air at 770 K it changes to Fe2(SO4)3 with a single Mössbauer line (width 0.33 mm/sec; isomeric shift 0.31 mm/sec) strikingly similar to line of NH4Fe(SO4)2. 相似文献
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A. Devendar Reddy S.G. Sathyanarayan G. Sivarama Sastry 《Solid State Communications》1982,43(12):937-940
D.C. electrical conductivity, DTA and coulometric studies on (NH4)3 H(SO4)2 single crystals are made. Conductivity is markedly anisotropic with maximum along c1 direction. A sudden jump in the conductivity plot along c1 direction at 413 K is supported by a large endothermic peak in DTA, confirming the presence of transition at this temperature. The values of activation energy calculated from conductivity measurements indicated that the charge carriers are protons. This was further confirmed by coulometric experiment where the gas evolved was hydrogen, as established by a gas chromatograph and the volume of H2 released agreed with that expected from electrolysis. The mechanism of protonic conduction in this crystal is discussed. 相似文献
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Yu. A. Boikov I. T. Serenkov V. I. Sakharov V. A. Danilov V. V. Afrosimov 《Physics of the Solid State》2011,53(10):2049-2053
The structure, orientation, and the response of electroresistance to magnetic field H and varying temperature T have been studied for 30-nm-thick La0.67Ba0.33MnO3 (LBMO) films. The deviation of the [001] direction in manganite layers from the normal to the plane of the (LaAlO3)0.29 + (SrAl0.5Ta0.5O3)0.71 substrate strictly corresponds to the vicinal angle of the latter. The minimum yield determined from 227-keV proton scattering
spectra is 0.025, signifying a high order of the cationic sublattice in the films. The biaxial compression of stable nuclei
of the manganite phase affects their stoichiometry, thus contributing to the depletion of LBMO films in the alkaline-earth
element. The maximum electroresistance values have been observed in the films grown at T
max ≈ 320 K, a temperature about 20 K lower than the Curie temperature of the corresponding bulk single crystals, and the maximum
magnetoresistance (MR ≈ −0.42, μ0
H = 2 T) occurs at T ≈ 300 K. At low temperatures (T < T
max/3) and μ0
H < 0.45 T, the electroresistance response of LBMO films to a magnetic field materially depends on the anisotropic magnetoresistance
and the intensity of hole scattering from domain walls; when μ0
H > 0.5 T, the major current-carrier relaxation mechanism is the interaction with magnons. 相似文献