Quantum Chemical Study On Electronic Transport Properties Of Two-dimension Graphene And C₆₀

The core of this paper mainly contains two parts,1. Transport properties of two-dimension graphene sheet and the effects of hexagonal haeckelite defectA systematic investigation of transport properties of two-dimension graphene and a hexagonal heackelite defect in which using first-principles is represent. Our results reveal that the transport properties of two-dimension graphene are very different from that of graphene nanoribbons in both armchair and zigzag directions. The transport properties along the armchair direction are semiconductor in two-dimension graphene. For armchair graphene nanoribbons, whose dimer line N satisfy N=3p-1(p is integer), are metallic, otherwise they are semiconductor. However, metallic properties obtained for zigzag direction in two-dimension graphene, and theâ… -â…¤curves present linear be-havior. For zigzag graphene nanoribbons, a clear current suppression observed under low bias when their zigzag line R are even. Different transport properties between armchair and zigzag directions in two-dimension graphene and the introducing hex-agonal haeckelite defect result several different patterns ofâ… -â…¤curves. The mechanism is the defect can block electronic transport, while the defect bands around Fermi level may offer electronic transmission channels.2. Transport properties and mechanism of C6o coupled to carbon nanotube elec-trodeBy applying non-equilibrium Green's functions in combination with the densi-ty-functional theory, we investigate the electronic transport properties of C60 coupled with carbon nanotube electrodes, i.e. CNT-C60-CNT. As a comparison, theâ… -â…¤curves of Li-C60-Li systems also represent in this article. The results show that the electronic transport properties are different completely between CNT-C60-CNT and Li-C6o-Li. In Li-C60-Li, the currents present linear relationship with biases. However, negative dif-ferential resistance and nonlinear conduction phenomenon observed in the I-V curves of CNT-C60-CNT. Then we discussed the mechanism ofâ… -â…¤characteristics of C60 coupled with carbon nanotubes. Our analysis result suggest that the conductance, the location of frontier molecular orbitals, HOMO and LUMO gap, the coupling of mo-lecular orbitals and electrode all play critical roles in CNT-C60-CNT.