Molecular one-dimensional topological insulators (1D TIs), described by the Su–Schrieffer–Heeger (SSH) model, are a new class of molecular electronic wires whose low-energy topological edge states endow them with high electrical conductivity. However, when these 1D TIs become long, the high conductance is not sustained because the coupling between the edge states decreases with increasing length. Here, we present a new design where we connect multiple short 1D SSH TI units linearly or in a cycle to create molecular wires with a continuous topological state density. Using a tight-binding method, we show that the linear system gives a length-independent conductance. The cyclic systems show an interesting odd−even effect, with unit transmission in the topological limit, but zero transmission in the trivial limit. Furthermore, based on our calculations, we predict that these systems can support resonant transmission with a quantum of conductance. We can further expand these results to phenylene-based linear and cyclic 1D TI systems and confirm the length-dependent conductance in such systems.

中文翻译：

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设计具有多个非平凡拓扑状态的长且高导电分子线

由 Su-Schrieffer-Heeger (SSH) 模型描述的分子一维拓扑绝缘体 (1D TI) 是一类新型分子电子线，其低能拓扑边缘态赋予它们高导电性。然而，当这些 1D TI 变长时，高电导不会持续，因为边缘状态之间的耦合随着长度的增加而降低。在这里，我们提出了一种新设计，我们将多个短的 1D SSH TI 单元线性或循环连接，以创建具有连续拓扑状态密度的分子线。使用紧束缚方法，我们表明线性系统给出了与长度无关的电导。循环系统表现出有趣的奇偶效应，在拓扑极限中有单位传输，但在平凡极限中传输为零。此外，根据我们的计算，我们预测这些系统可以支持具有电导量子的谐振传输。我们可以进一步将这些结果扩展到基于亚苯基的线性和循环一维 TI 系统，并确认此类系统中的长度依赖电导。