Based on first-principles calculations and tight-binding model analysis, we propose monolayer graphdiyne as a candidate material for a two-dimensional higher-order topological insulator protected by inversion symmetry. Despite the absence of chiral symmetry, the higher-order topology of monolayer graphdiyne is manifested in the filling anomaly and charge accumulation at two corners. Although its low energy band structure can be properly described by the tight-binding Hamiltonian constructed by using only the p_z orbital of each atom, the corresponding bulk band topology is trivial. The nontrivial bulk topology can be correctly captured only when the contribution from the core levels derived from p_x,y and s orbitals are included, which is further confirmed by the Wilson loop calculations. We also show that the higher-order band topology of a monolayer graphdyine gives rise to the nontrivial band topology of the corresponding three-dimensional material, ABC-stacked graphdiyne, which hosts monopole nodal lines and hinge states.

基于第一性原理计算和紧密结合模型分析，我们提出单层石墨二炔作为反对称性保护的二维高阶拓扑绝缘子的候选材料。尽管没有手性对称性，但单层石墨二炔的高阶拓扑结构表现在两个角落的填充异常和电荷积累中。虽然它的低能量带结构可通过适当地描述的紧密结合哈密顿构建通过仅使用p _Ž轨道各原子的，相应的整体能带拓扑是微不足道的。仅当来自p _x，y和s的核心层的贡献时，才能正确捕获非平凡的体拓扑包括轨道，威尔逊循环计算进一步证实了这一点。我们还表明，单层石墨烯的高阶能带拓扑结构会引起相应的三维材料ABC堆积的石墨二炔的非平凡带能拓扑结构，该材料具有单极节点线和铰链状态。