We systematically study geometries and band structures of two-dimensional group-V bilayer materials, i.e. phosphorene, arsenene and antimonene. Among the four stacking structures (AA, AB, AC, and AD), the AB stacking structures are found to be the largest band gaps and to be the most energetically stable. We find novel band structures on the whole Brillouin zone edges: four bands have close energies and two of the four bands have the same energy in many cases. We analyze the characteristic features of the band structures based on the group theory and clarify that the features depend on the space group of each stacking structure. We also find that the band splits due to the interlayer interaction is very small and this interaction becomes large as atoms become heavy.

我们系统地研究了二维V族双层材料，即磷烯、砷烯和锑烯的几何形状和能带结构。在四种堆叠结构（AA、AB、AC 和 AD）中，AB 堆叠结构被发现是最大的带隙并且是最能量稳定的。我们在整个布里渊区边缘发现了新的能带结构：四个能带具有接近的能量，并且在许多情况下，四个能带中的两个具有相同的能量。我们基于群论分析了能带结构的特征，并阐明了这些特征取决于每个堆叠结构的空间群。我们还发现，由于层间相互作用导致的能带分裂非常小，并且随着原子变重，这种相互作用会变大。