低对称性扭曲对通过金属原子链传输电子的影响:什么时候分子电线真正"断裂"?
Vihar P Georgiev1, John E McGrady
1Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom.
Journal of the American Chemical Society
|July 14, 2011
概括
在分子电子学中,金属原子链中的电子运输令人惊的是并非由非局部化的pi轨道主导. 相反,更高能量的西格玛轨道传导电流,即使有结构扭曲.
科学领域:
- 分子电子学分子电子学
- 量子化学是一种量子化学.
- 材料科学是一种材料科学.
背景情况:
- 分子轨道的移位通常被认为对分子电子中的电流流程至关重要.
- 结构对称性,就像统一的结合长度一样,通常与轨道移位有关.
- 之前的研究提出了一个非局部化的π框架作为Cr{3}{dpa}{4}{NCS}{2}链中的初级传导通路.
研究的目的:
- 为了研究轨道移位,结构对称性和在延长的金属原子链中电子运输之间的关系.
- 挑战传统的假设,将移位和导电性联系在一起.
- 为了确定Cr(3)(dpa)(4)(NCS)(2) 中电子运输的主导轨道.
主要方法:
- 密度函数理论 (DFT) 的计算.
- 非平衡的格林函数 (NEGF) 形式主义.
- 分析Cr(3) 金属原子链中的低对称性扭曲.
主要成果:
- 低对称性扭曲降低了π通道的有效性,但对于低偏差运输无关,因为它们低于费米水平.
- 较高的 σ 轨道,而不是 π 轨道,是电子运输的主要途径.
- 导电量略有增加,因为由于扭曲,σ(nb) 通道更接近费米水平.
结论:
- 金属链中的结构和功能之间的关系是微妙的和反直觉的.
- 轨道对称性和能量水平,而不仅仅是移位,决定导电性.
- 这些发现对解释分子电子学中扫描探头显微镜技术的实验数据具有重大意义.
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