Oscillation of Conductance in Molecular Junctions of Carbon Ladder Compounds
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- 作者：Tomofumi Tada ; Daijiro Nozaki ; Masakazu Kondo ; Shinya Hamayama ; and Kazunari Yoshizawa
- 刊名：Journal of the American Chemical Society
- 出版年：2004
- 出版时间：November 3, 2004
- 年：2004
- 卷：126
- 期：43
- 页码：14182 - 14189
- 全文大小：242K
- 年卷期：v.126,no.43(November 3, 2004)
- ISSN：1520-5126
文摘
The electrical conductances of dithiolates of polyacene (PA(n)DTs) and polyphenanthrene (PPh(n)DTs), which are typical carbon ladder compounds, are calculated by means of the Landauer formulationcombined with density functional theory, where n is the number of benzene rings involved. Surface Greenfunction used in the Landauer formulation is calculated with the Slater-Koster parameters. Attention isturned to the wire-length dependence of the conductances of PA(n)DTs and PPh(n)DTs. The damping ofconductance of PA(n)DTs is much smaller than that of PPh(n)DTs because of the small HOMO-LUMOgaps of PA(n)DTs. PA(n)DTs are thus good molecular wires for nanosized electronic devices. Conductanceoscillation is found for both molecular wires when n is less than 7. The electrical conductance is enhancedin PA(n)DTs with even-numbered benzene rings, whereas it is enhanced in PPh(n)DTs with odd-numberedbenzene rings. The observed conductance oscillation of PA(n)DTs and PPh(n)DTs is due to the oscillationof orbital energy and electron population. Other 
-conjugated oligomers (polyacetylene-DT, oligo(thiophene)-DT, oligo(meso-meso-linked zinc(II) porphyrin-butadiynylene)-DT, oligo(p-phenylethynylene)-DT, and oligo(p-phenylene)-DT) are also studied. In contrast to PA(n)DTs and PPh(n)DTs, the five molecular wires showordinary exponential decays of conductance.
-conjugated oligomers (polyacetylene-DT, oligo(thiophene)-DT, oligo(meso-meso-linked zinc(II) porphyrin-butadiynylene)-DT, oligo(p-phenylethynylene)-DT, and oligo(p-phenylene)-DT) are also studied. In contrast to PA(n)DTs and PPh(n)DTs, the five molecular wires showordinary exponential decays of conductance.