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A theoretical model is summarized into the shorter vector principle. It is used to predict the topological structure of wave function and the oscillation rule of energy gap in various types of finite carbon nanotubes (CNTs). The theoretical model indicates that the characteristics of the electronic states only depend on the nanotube size and its symmetry along the shorter vector direction. In this direction, the wave functions of the original 3m (or 3m/2) periodicity are also suitable for armchair, chiral and zigzag finite CNTs with the C2 (Cs), C1 and Cn point groups, respectively. Energy gaps present the oscillation with 3m (or 3m/2) or odd-even n. The first principle calculations for some prototype systems are performed. The results are consistent with the theoretical model. 相似文献
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MgO缺陷和不规则表面吸附Cl2的电子结构研究 总被引:2,自引:0,他引:2
采用从头算程序对MgO表面 3种不同配位位置吸附Cl2 的构型进行优化 ,并用扩展休克尔紧束缚 (EHT)晶体轨道方法对MgO的缺陷和不规则表面吸附Cl2的可能构型进行能带计算 ,讨论了吸附前后能带组成和成键性质的变化。研究表明 :MgO表面吸附Cl2 将更趋向于吸附在O原子上而非Mg原子上 ,而且在 3种配位中MgO表面三配位氧最有利于吸附Cl2 ;吸附时 ,电子从O原子转移到Cl2 分子的反键轨道 ,但是各种吸附构型的MgO表面对Cl2 的吸附作用均比较微弱 ,是典型的物理吸附。 相似文献
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采用DFT/BLYP方法对NbC(001)和(111)面的电子结构进行研究。计算结果表明,对于NbC(001)表面,其表面态主要集中于费米能级(EF)下方约4.5eV附近区域,并以表面Nb原子和C原子为主要成分。O2分子在该表面吸附时,趋向于吸附在表面Nb原子上。对于NbC(111)表面,其表面态集中在EF下方0.02.0eV区域,靠近EF的态具有较高的表面活性,其主要成分为表面Nb原子的4dxz/dyz成分。上述结论与光电子能谱实验结果基本一致;但由于金属原子d电子数的差异导致NbC(111)表面态成分与类似的TiC化合物并不相同。 相似文献
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合成了一种新颖有机-无机杂化配位聚合物{[C12H28N2] [(Pb3I8)(DMF)2]•2DMF}n, 并进行了红外、紫外、热重表征, 采用X射线衍射方法确定了晶体结构. 结构解析表明, 整个分子由阳离子(双质子化的N,N'-二丁基哌嗪)及聚阴离子链([(Pb3I8)(DMF)2]n2-)组成, 它们之间由静电作用结合在一起形成一维链状配位聚合物. 依据晶体结构数据, 采用Gaussian03程序对产物进行量子化学计算. 相似文献
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1 INTRODUCTION The interfaces between metals and oxide play a vital role in many industrial applications: hetero- geneous catalysis, microelectronics, thermal barriers, corrosion protection, metal processing and so on[1]. In catalysis, the choice of metal and oxide support is critical in order to obtain a desired reactivity and selectivity[2]. This is due in part to the inherent reac- tivity of the two components. Also the size and shape of the metal particle, which depend on the choice… 相似文献
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用赝势从头计算方法研究Hf8C12多面体.先对T和Td分子构型作几何优化,发现Td对称构型比T构型稳定.利用非限制的Hartre Fock方法及自然键轨道分析研究Td构型的Hf8C12基团,结果表明:Hf8C12存在三种自旋不同的基态,这种基态的多样性与成键机制、电子组态和电子能谱分布密切相关.其中S=0时,Hf8C12主要是由外四面体Hf原子与类乙烯C2单元形成极性共价键构成.S=1时,6个类乙炔C2单元吸附在Hf8金属框架.S=2时,部分C2中的pπ键断裂与Hf原子形成d←pπ键.进一步分析发现,Td对称性的结构模型为(Hf8)+4.5(C-0.752)6,在高自旋态下具有铁磁性,电子能级分布及其能隙随自旋态而变化.
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The paper reports the formation and crystal structure of dihydronitidine, expounds thereasons and conditions of easily formed oxynitidine, and discusses anticancer mechanism ofnitidine (cation). The crystallographic parameters of dihydronitidine are: space group P2_(1/n),a= 12.54(1), b = 9. 148(5), c = 14.748(8)A, β= 92. 12(6)°,Z =4. 4108 independent reflec-tions were collected within the range of 3°≤2θ≤54°, of which 2137 intensity data with I≥3σ(I) were used in the structural determination. The crystal structure has been refined byfull matrix least-square method to a final R of 0.050. 相似文献