富勒稀C36的电子结构与电子传导

本文采用基于第一性原理的密度泛函理论和非平衡格林函数方法研究了C36分子的电子结构和电子传导特性．本文以Au(1,1,1)为电极分别建立了4个电子输运模型,分别计算了他们的电子传输概率、伏安曲线,同时分析了产生这些分子器件电子输运性质的原因．研究计算结果发现, C36的电子输运主要发生在分子壳上,当左、右电极分别连接在第6号和第35号碳原子两端时,C36的电子输运性能最好,伏安曲线显示该分子具有半导体特性．     

C50富勒烯分子的电子结构与传输特性研究

本文构建了Au原子面为电极的富勒烯C50分子的电子输运模型, 使用非平衡格林函数方法(Non-equilibrium Green's function, NEGF)对构建的Au电极和C50分子构成的分子器件进行了电子传输性质的计算. 通过计算得出了电子透射谱、电导曲线和电流电压曲线, 分析了产生这个分子器件电子输运性质的原因. 研究计算结果发现：C50分子具有量子器件的开关特性,并具有明显的半导体特征.     

空富勒烯C36和嵌入Mg原子的C36分子的电子学特性研究

采用基于密度泛涵理论的第一性原理和非平衡格林函数方法研究了富勒烯C36分子和以金原子面为电极的Au-S-C36-S-Au电子传输系统的电子结构和传输特性.然后将镁原子嵌入C36笼腔内得到了一个新的分子器件Mg@C36,接金电极后建立了它的电子传输系统Au-S-Mg@C36-S-Au,并且得出了这一系统的电子能级、分子轨道分布、传输概率、态密度、伏安特性和电导曲线.结果显示C36和Mg@C36的电子传导主要集中在分子壳上,且系统Au-S-C36-S-Au中的电子传输主要分布在分子壳的外侧,而系统Au-S-Mg@C36-S-Au中的电子传输在分子壳外侧和内侧的近似相同,二个系统都有着非线性的Ⅰ-Ⅴ特性和电导曲线.     

Mg、Na原子嵌入对富勒烯C32分子的电子结构与传输特性的影响

采用基于第一性原理的密度泛函理论（DFT）和非平衡格林函数（NEGF）方法对嵌入Na和Mg的富勒烯C₃₂分子Mg@C₃₂和Na@C₃₂连接面电极Au（1,1,1）所构成的分子器件进行了电子结构与传输特性的理论研究.得出了2个分子桥的电子结构、电子传输概率及伏安（Ⅰ-Ⅴ）特性.分析了影响电子结构与电子传输特性的因素.结果表明,金属Mg原子和Na原子的嵌入都大大增强了C₃₂分子的电子传输性能.     

Au电极连接富勒烯C32分子的电子结构与传输特性

采用基于密度泛函理论(DFT)和非平衡格林函数(NEGF)的第一性原理方法对富勒烯C₃₂分子及在C₃₂分子的距离最远的两个碳原子处连接Au(1,1,1)电极的分子器件进行了电子结构和电子输运性质的研究.考虑到中间分子与Au电极间距离变化的情况,通过计算得出了在不同距离下分子器件的电子传输谱和I-V特性,分析了各器件的电子结构和电子输运特性产生的原因,并分析了电极与中间分子的连接距离及门电压对分子器件电子输运的影响.得出了电极与所连接的中间分子之     

空富勒烯C36和嵌入Mg原子的C36分子的电子学特性研究

采用基于密度泛涵理论的第一性原理和非平衡格林函数方法研究了富勒烯C36 分子和以金原子面为电极的Au-S-C36-S-Au电子传输系统的电子结构和传输特性.然后将镁原子嵌入C36笼腔内得到了一个新的分子器件Mg@C36,接金电极后建立了它的电子传输系统Au-S-Mg@C36-S-Au,并且得出了这一系统的电子能级、分子轨道分布、传输概率、态密度、伏安特性和电导曲线. 结果显示C36 和 Mg@C36的电子传导主要集中在分子壳上,且系统Au-S-C36-S-Au中的电子传输主要分布在分子壳的外侧,而系统Au-S-Mg@C36-S-Au中的电子传输在分子壳外侧和内侧的近似相同,二个系统都有着非线性的I-V特性和电导曲线。     

压缩变形对C20富勒烯分子电子传输特性的影响

分别采用分子动力学方法与扩展的H櫣ｃｋｅｌ方法分析了双Ａｕ电极作用下 ,未变形以及压缩量为 10 %、2 0 %的C2 0 富勒烯分子的几何构形与电子结构 ;采用扩展的H櫣ｃｋｅｌ方法与格林函数方法计算了三种Ａｕ电极 压缩C2 0 分子 Au电极体系的导电性 .研究结果表明 ,C2 0 分子与Au电极之间的“接触”改变了C2 0 分子的电子结构 ;C2 0 分子与Au电极之间的结合既有共价键的成分 ,又有离子键的成分 ,跟Au电极对C2 0 分子的压缩量紧密相关 ;压缩的C2 0 分子具有更好的导电性能 .     

C72 富勒烯的电子结构与电子传导研究

本文利用基于密度高泛函理论(DFT)和非平衡格林函数的第一性原理方法对富勒烯C72分子及连接电极构成的C72分子器件进行了电子结构及电子输运性质的研究.计算出了电子透射谱和分子轨道分布,分析了器件的电子结构和输运性质的产生原因. 结果显示C72分子器件的电子传输主要集中在分子壳上. 伏安曲线显示C72分子具有半导体特征.     

C50富勒烯分子的电子结构与传输特性研究

本文构建了Au原子面为电极的富勒烯C₅₀分子的电子输运模型,使用非平衡格林函数方对构建的以Au原子面为电极的C₅₀分子的电子输运模型进行了电子传输性质的计算.通过计算得出了电子透射谱、电导曲线和电流电压曲线,分析了此分子器件产生电子输运性质的原因.研究计算结果发现:C₅₀分子具有量子器件的开关特性,并具有明显的半导体特征.     

富勒烯C32分子器件结构和传导特性的理论研究

利用基于第一性原理的密度泛函理论(DFT)和非平衡格林函数(NEGF)方法对富勒烯C32分子及在C32的距离最远的两个碳原子处外接Li电极的C32分子器件进行了电子结构、电子传输性质的研究。设计了C32笼内嵌入Mg原子,外接Li电极的分子器件。通过计算,得出了两个分子器件的电子传输谱,分析了他们的电子结构和电子输运特性。说明了C32分子器件的电子传输主要集中于C32分子的壳表上,并且分子球的内侧和外侧的电子传输相近似。在C32分子内部嵌入Mg原子后,分子器件的电子传输仍主要集中在分子表面上,但在系统Mg@C32中,表面内侧的电子传输要比表面外侧的电子传输强。通过比较,结果表明两种富勒烯分子的电子传输性能顺序为Mg@C32>C32。     

C77N+异构体的稳定性和电子光谱研究

用INDO系列方法对C78(C2V)的等电子体C77N+的所有21种可能异构体进行系统的理论研究.研究结果表明,最稳定异构体是由C78(C2V)沿Y方向椭球短轴所穿过的C(78)-C(73)键上的原子C(78)被N+取代所形成,椭球长轴附近的原子被取代所形成的异构体能量较低,取代位置附近易成为进一步反应的中心.用INDO/SCI方法计算了C77N+电子光谱,表明其吸收峰与C78(C2V)相比发生红移,对特征吸收峰进行了理论指认,讨论吸收峰红移的原因.     

The configuration and electronic state of SO3 adsorbed on Au surface

We evaluated the adsorption of SO₃ molecule on Au (1 1 1) surface using first principles calculation by a slab model with a periodic boundary condition. We find that there are six stable adsorption configurations on an Au surface, where the SO₃ molecule is adsorbed above the three-fold fcc and hcp hollow sites and on the atop site. In two of these configurations, S and two O atoms are bound to the Au atoms, the next two configurations have all the three O atoms bound to the Au surface atoms, and the last two configurations have the S atom bound to an Au surface atom on the atop site and O atoms situated above the hollow sites. In these configurations, the electronic structures of SO₃ on the Au surface show that molecular orbitals of SO₃ and those of the Au surface are hybridized in the active metal d-band region, that the localized molecular orbitals in SO₃ are stabilized, and that charge is transferred from Au to S 3p by SO₃ adsorption on the Au surface though there is little other interaction of the S and O (bound to Au) component with Au. Moreover, the bond between the S and O atoms bound to Au is weakened due to SO₃ adsorption on the Au surface due to the charge polarization of the O-Au bond. This interaction is likely to encourage the S-O bond to break.     

Electronic transmission of three-terminal pyrene molecular bridge

This paper investigates theoretically the electronic transmission spectra of the three terminal pyrene molecular bridge and the quantum current distribution on each bond by the tight-binding model based on nonequilibrium Green's function and the quantum current density approach, in which one π molecular orbital is taken into account per carbon atom when the energy levels and HOMO-LUMO gap are obtained. The transmission spectra show that the electronic transmission of the three terminal pyrene molecular bridge depends obviously on the incident electronic energy and the pyrene eigenenergy. The symmetrical and oscillation properties of the transmission spectra are illustrated. A novel plus-minus energy switching function is found. The quantum current distribution shows that the loop currents inside the pyrene are induced, and some bond currents are much larger than the input and the output currents. The reasons why the loop currents and the larger bond currents are induced are the phase difference of the atomic orbits and the degeneracy of the molecular orbits. The calculations illustrate that the quantum current distributions are in good agreement with Kirchhoff quantum current conservation law.     

嵌入锂原子的zigzag型单壁碳纳米管的电子传导特性

运用基于第一性原理的密度泛函理论（DFT）的非平衡格林函数（NEGF）方法对Li原子嵌入后的zigzag型单壁碳纳米管(SWCNT)的电子输运性质进行了研究.在构建和优化了Li原子嵌入的zigzag型单壁碳纳米管的电子输运模型后,研究了该系统的电子传输概率、能态密度、电子透射谱,还研究了电子能量和偏置电压设置与变化对其电子输运特性的影响.结果显示zigzag型单壁碳纳米管嵌入Li原子后,电子输运特性发生了较大变化,具有电子输运拓宽效应和量子台阶复苏效应. 关键词： Li原子 碳纳米管 电子输运 拓宽效应     

Au@Sin: Growth behavior, stability and electronic structure

The configurations, stability, and electronic structure of AuSin (n=1-16) clusters have been investigated within the framework of the density functional theory at the B3PW91/LanL2DZ and PW91/DNP levels. The results show that the Au atom begins to occupy the interior site for cages as small as Si₁₁ and for Si₁₂ the Au atom completely falls into the interior site forming Au@Si₁₂ cage. A relatively large embedding energy and small HOMO-LUMO gap are also found for this Au@Si₁₂ structure indicating enhanced chemical activity and good electronic transfer properties. All these make Au@Si₁₂ attractive for cluster-assembled materials.     

Formation of Ag2, Au2 and AgAu particles on MgO(1 0 0): DFT study on the role of support-induced charge transfer in metal-metal interactions

The formation of Ag₂, Au₂ and AgAu particles oriented perpendicularly to the MgO(1 0 0) surface was studied using the density functional theory. While the support induces a slight enhancement of the Ag-Ag bond (by 0.3-0.4 eV), the Au-Au bond is strongly enhanced (by 0.8-1.1 eV). Concerning the bimetallic particle, the Ag-Au bond stabilization depends on the relative position of each atom. Thus, in general terms, the strength of the metal-metal bond is determined by the nature of the terminal atom; the bond is stronger in Au-terminal particles. The partial electronic charge transfer to the terminal Au atom and its ability to polarize this charge are responsible for this energetic stabilization.     

Counting electrons transferred through a thin alumina film into Au chains

Low-temperature STM measurements combined with density functional theory calculations are employed to study the adsorption of gold on alumina/NiAl(110). The binding of Au monomers involves breaking of an oxide Al-O bond below the adatom and stabilizing the hence undercoordinated O ion by forming a new bond to an Al atom in the NiAl. The adsorption implies negative charging of the adatom. The linear arrangement of favorable binding sites induces the self-organization of Au atoms into chains. For every ad-chain, the number of transfer electrons from the support is determined by analyzing the node structure of the corresponding highest occupied molecular orbital.     

Structural and electronic properties of endohedral doped SWCNTs: A DFT study

The structural and electronic properties of semiconductors (Si and Ge) and metal (Au and Tl) atoms doped armchair (n, n) and zigzag (n, 0); n=4–6, single wall carbon nanotubes (SWCNTs) have been studied using an ab-initio method. We have considered a linear chain of dopant atoms inside CNTs of different diameters but of same length. We have studied variation of B.E./atom, ionization potential, electron affinity and HOMO–LUMO gap of doped armchair and zigzag CNTs with diameter and dopant type. For armchair undoped CNTs, the B.E./atom increases with the increase in diameter of the tubes. For Si, Ge and Tl doped CNTs, B.E./atom is maximum for (6, 6) CNT whereas for Au doped CNTs, it is maximum for (5, 5) CNTs. For pure CNTs, IP decreases slightly with increasing diameter whereas EA increases with diameter. The study of HOMO–LUMO gap shows that on doping metallic character of the armchair CNTs increases whereas for zigzag CNTs semiconducting character increases. In case of zigzag tubes only Si doped (5, 0), (6, 0) and Ge doped (6, 0) CNTs are stable. The IP and EA for doped zigzag CNTs remain almost independent of tube diameter and dopant type whereas for doped armchair CNTs, maximum IP and EA are observed for (5, 5) tube for all dopants.