Solomon Paul M, Lang Norton D
IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, USA.
ACS Nano. 2008 Mar;2(3):435-40. doi: 10.1021/nn700253p.
We study transport and charge control in a gated 4,4'-biphenyl diradical molecular transistor using self-consistent density-functional calculations. We track both electron-like and hole-like conduction and relate it to the field dependence of current-carrying pi-derived states. Owing to the coupling between the two benzene rings, the pi-states become segregated into extended, current-carrying states and localized states. Under application of the source/drain field, along the axis of the molecule, the localized pi-states become split, while the extended states become polarized and screen the field. The localized states act like isolated islands within the molecule--while they make a substantial contribution to the density of states, they make only a small contribution to transport.
我们使用自洽密度泛函计算方法研究了栅控4,4'-联苯双自由基分子晶体管中的输运和电荷控制。我们追踪了电子型和空穴型传导，并将其与载流π衍生态的场依赖性联系起来。由于两个苯环之间的耦合，π态被分离为扩展的载流态和局域态。在源极/漏极场沿着分子轴施加时，局域π态发生分裂，而扩展态发生极化并屏蔽该场。局域态在分子内就像孤立的岛屿——虽然它们对态密度有很大贡献，但对输运的贡献却很小。
