In the last years, 2D materials beyond graphene have a great interest in the field of nanoelectronics and nano-optics applications. Based on the density theory and beyond (i.e., GW, RPA, and BSE), we study the vibrational, electronic, and optical properties of a new 2D GaOBr monolayer. In this framework, we have found that this 2D sheet is dynamically stable, which determined by their phonon dispersion. Our GW results show that the bandgap energy value of this sheet is ~ 5.20 eV, which is larger than the bandgaps of the REOBr monolayers (RE = Tb, Dy, Ho, Er, and Tm). Surprisingly, for the valence band, we have obtained two maxima, one is located at Γ point and the other appears at the X-point. The influence of an electric field on the electronic band structures of the GaOBr monolayer is also studied. In this framework, we obtained the application of the electric field significant changes in the position of VBM and CBM. Furthermore, we found that the BSE approach is the best technique to represent the dielectric function of GaOBr.

近年来，石墨烯以外的2D材料在纳米电子学和纳米光学应用领域引起了极大兴趣。基于密度理论及以后的理论（即GW，RPA和BSE），我们研究了新型2D GaOBr单层的振动，电子和光学性质。在此框架中，我们发现该2D图纸是动态稳定的，这取决于其声子色散。我们的GW结果表明，该片的带隙能值为〜5.20 eV，大于REOBr单层的带隙（RE = Tb，Dy，Ho，Er和Tm）。出乎意料的是，对于价带，我们获得了两个最大值，一个位于Γ点，另一个出现在X点。还研究了电场对GaOBr单层电子能带结构的影响。在这个框架中，我们获得了电场的应用，VBM和CBM的位置发生了显着变化。此外，我们发现BSE方法是代表GaOBr介电函数的最佳技术。