Within the last several years, a large number of experimental and theoretical studies of ballistic electron transport through atomic and molecular wires have been carried out. Future research on transport properties can be expected to lead to new discoveries of nanoscience and novel fabrications of electronic devices.
In this presentation, we present the electron-conduction properties of C60 molecules suspended between semi-infinite gold electrodes using first-principles calculations within the framework of the density functional theory [1]. We employ the first-principles calculation code, RSPACE04, which combines the real-space finite difference approach with the overbridging boundary matching method [2] to elucidate the relationship between geometrical structures and electron transport properties of nanostructures suspended between two semi-infinite electrodes. Our results indicate that the conductance of the C60 dimer is ~0.1 G0 owing to the scattering of incident electrons at the junction between the molecules, whereas that of the C60 monomer is ~1 G0. By encapsulating Li atoms in their cages, the dimer exhibits good conductivity. The energy of the unoccupied molecular orbitals at the junction shifts down to the Fermi level, and as a consequence, the conductance of the Li@C60 dimer significantly increases. To explore the doping mechanism of the C60 bridges, we also compared the energy band structures of the infinite C60, Li@C60, and Li wires and found that the Li@C60 wire is a conductor due to the electron transfer from the Li atom to the fullerene, while the other wires are insulators.
References:
[1] T. Ono and K. Hirose, Phys. Rev. Lett. 98, 026804 (2007).
[2] K. Hirose, T. Ono, Y. Fujimoto and S. Tsukamoto, First-Principles Calculations in Real-Space Formalism, Electronic Configurations and Transport Properties of Nanostructures (Imperial College Press, London, 2005).
First-Principles Study of Electron Transport through Fullerene Wires.
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