Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing, People's Republic of China.
Nanotechnology. 2010 Dec 10;21(49):495202. doi: 10.1088/0957-4484/21/49/495202. Epub 2010 Nov 16.
The electronic transport properties of a single benzene molecule connected to gold and platinum electrodes through the direct Au-C or Pt-C bond are investigated by using a self-consistent ab initio approach that combines the non-equilibrium Green's function (NEGF) formalism with density functional theory (DFT). Our calculations show that the benzene molecule can bind to the Au(111) surface via direct Au-C bond at the adatom, atop and bridge sites. The largest zero-bias conductance is calculated for the bridge site but it is only G = 0.37G(0) (G(0) = 2e(2)/h). In contrast benzene binds to the Pt(111) surface via direct Pt-C bond only at the adatom and atop sites. When the binding site is the adatom a stable molecular junction forms with a zero-bias conductance as large as 1.15G(0). This originates from the efficient coupling between the extended π-type highest occupied molecular orbital of benzene and the conducting states of the Pt electrodes via the 5d(xz) atomic orbital of the adatoms. The calculated transmission is robust to the choice of DFT functionals, illustrating the potential of the Pt-C bond for constructing future molecular electronic devices.
通过将非平衡格林函数（NEGF）形式与密度泛函理论（DFT）相结合的自洽方法，研究了通过直接 Au-C 或 Pt-C 键连接到金和铂电极的单个苯分子的电子输运性质。我们的计算表明，苯分子可以通过直接的 Au-C 键在 adatoms、 atop 和桥位上与 Au(111)表面结合。对于桥位，计算出的零偏压电导最大，但仅为 G = 0.37G(0)（G(0) = 2e(2)/h）。相比之下，苯分子仅通过直接的 Pt-C 键与 Pt(111)表面结合，只能在 adatoms 和 atop 位点上。当结合位点为 adatoms 时，形成稳定的分子结，零偏压电导高达 1.15G(0)。这源于苯的扩展 π 型最高占据分子轨道与 Pt 电极的导带态之间通过 adatoms 的 5d(xz)原子轨道的有效耦合。计算出的传输是稳健的，对 DFT 泛函的选择不敏感，这说明了 Pt-C 键在构建未来分子电子器件方面的潜力。
