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Ab Initio Investigations of the Transport Properties of Haeckelite Nanotubes and Graphene Junctions

Author: LiZuoFei
Tutor: LiBingRui
School: Lanzhou University
Course: Physical and chemical
Keywords: Transport properties Lanzhou University Carbon nanotubes Connection unit Transport coefficients Disulfide bonds Thesis Negative resistance phenomenon Density functional The structural unit
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 107
Quote: 1
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Abstract


The 1.Haeckelite nanotube transport properties of Ab initio theoretical study by first-principles ab initio methods, we systematically studied the electronic transport properties of nanotubes Haeckelite. In the calculation, respectively make Haeckelite nano pipe ends of the nanotubes connected to the electrode or a gold electrode. For the former, the IV characteristic curve calculated nonlinear negative resistance characteristic. For the latter, but did not observe the phenomenon of negative resistance. This difference is due to the conditions of the applied bias, the electrode band caused by the mismatch. By careful analysis of the correspondence between the intrinsic channel and electrode energy band, we successfully explain this phenomenon, and pointed out that when the electrode size is reduced to the nanometer scale, this phenomenon is widespread. Theoretical study of carbon nanotube-graphene molecular junction we have designed a series of novel covalently linked carbon nanotube-graphene molecular junction, including linear, T-, and H-molecule junction, and density functional theory Calculation of their electronic properties. In addition, we also used the non-equilibrium Green equation systematic study of the electronic transport properties of various molecular junction. The calculation results show that the fine structure can be achieved through the flexible application of covalent connectivity solutions. And the introduction of the connection unit to play a basic connectivity, but also bring many interesting geometric and electronic properties. We obtained the following results: (i) an amide bond is a rigid connection, both ends of the structural unit does not rotate freely; disulfide bond belong to the flexible connector, both ends of the structural unit can be relatively easily rotated. (Ii) the linked molecule Results for amide bond generated will increase as the number of amide bond rose rapidly. Molecular Results generated as a connection unit for disulfide bond can be decreased along with the increase in proportion to the disulfide bond. Chair carbon nanotube-graphene nano with molecular junction formation reaction tends to be exothermic, and zigzag carbon nanotube-graphene nano with molecular junction formation reaction tends to be endothermic. (Iii) better conductivity than an amide bond to the disulfide bond, and the connecting unit will significantly affect the electron transport properties of the molecular junction. (Iv) For T-molecule junction, the electronic transport properties are mainly determined by the main chain, branched secondary. (V) for the H-type molecular junction, the interlayer electron transporting capability is relatively poor. Based on the H-type molecular junction can be further design a more complex three-dimensional network structure, this structure may be the prototype of the carbon-based electronic circuits.

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