The Su–Schrieffer–Heeger (SSH) model is a prototypical one-dimensional (1D) diatomic lattice model for non-trivial topological phases and topological excitations. Theoretically, many variations and extensions of the SSH model have been proposed and explored to better understand the novel aspects of topological physics in low dimensions on the nanoscale. However, the outstanding challenge remains to find real nanomaterials with robust structural stability for realizing the 1D topological states. Here, we develop an extended version of the SSH model with multi-atomic bases of four, six and eight atoms and an imposed screw rotation symmetry. Furthermore, based on first-principles calculations, we demonstrate the realization of this model in transition metal monochalcogenide M₆X₆ (M = Mo and W; X = S, Se and Te) nanowires. The topological features of the doped M₆X₆ nanowires are confirmed with non-trivial edge modes and e/2 fractional charges, representative of the 1D non-trivial Zak phase. Our finding not only sheds new light on our fundamental understanding of 1D topological physics, but also significantly extends the scope of 1D topological materials that will attract immediate experimental interest, since isolated M₆X₆ nanowires have already been synthesized in experiments.

中文翻译：

---

过渡金属单硫族化物纳米线中的一维拓扑相。

Su-Schrieffer-Heeger（SSH）模型是非平凡的拓扑阶段和拓扑激发的典型一维（1D）双原子晶格模型。从理论上讲，已经提出并探索了SSH模型的许多变体和扩展，以更好地理解纳米尺度低维拓扑物理的新颖方面。然而，寻找具有鲁棒结构稳定性的真正纳米材料以实现一维拓扑状态仍然是一项艰巨的挑战。在这里，我们开发了SSH模型的扩展版本，该模型具有由四个，六个和八个原子组成的多原子碱基，并具有强制的螺杆旋转对称性。此外，基于第一性原理计算，我们证明了该模型在过渡金属单硫属元素化物M ₆ X _{6中的实现}（M = Mo和W； X = S，Se和Te）纳米线。掺杂的M ₆ X ₆纳米线的拓扑特征已通过非平凡的边缘模式和e / 2分数电荷得以确认，代表一维非平凡的Zak相。我们的发现不仅为我们对一维拓扑物理的基本理解提供了新的思路，而且还大大扩展了一维拓扑材料的范围，这将引起立即的实验兴趣，因为在实验中已经合成了分离的M ₆ X ₆纳米线。