BiOI is reported to be a promising photocatalytic material for splitting water and decomposing pollutants in the visible range. However, previous investigations focus mainly on its photocatalytic property and other properties are not well studied. Here we put our effort to study the electronic, elastic and vibrational properties of BiOI. The results indicate that BiOI is an indirect narrow band gap semiconductor. Bi–O bonds have both covalent and ionic characteristics while Bi–I bonds may have more ionic nature. BiOI is mechanically and dynamically stable. However, calculated directional bulk and Young's moduli reveal that it is seriously mechanically anisotropic, originating from its layered structure. Its infrared absorption spectrum is simulated and four peaks are found. The origins of these peaks are explored based on the calculated Born effective charges and vibrational eigenvectors at the Brillouin zone center. In addition, the dielectric constants of BiOI are computed and discussed. We hope our study will enrich the knowledge of BiOI and other similar materials.

据报道，BiOI 是一种很有前途的光催化材料，用于在可见光范围内分解水和分解污染物。然而，以前的研究主要集中在其光催化性能上，其他性能没有得到很好的研究。在这里，我们努力研究 BiOI 的电子、弹性和振动特性。结果表明BiOI是间接窄带隙半导体。Bi-O 键具有共价和离子特性，而 Bi-I 键可能具有更多的离子特性。BiOI 机械和动态稳定。然而，计算的方向体积和杨氏模量表明它具有严重的机械各向异性，源于其层状结构。模拟其红外吸收光谱，发现四个峰。基于布里渊区中心计算的玻恩有效电荷和振动特征向量来探索这些峰的起源。此外，还计算和讨论了 BiOI 的介电常数。我们希望我们的研究能够丰富 BiOI 和其他类似材料的知识。