Predicting Irida-Silicene: A Novel 2D Silicon Allotrope

Two-dimensional (2D) silicon-based materials have garnered significant attention for their promising properties, making them suitable for various advanced technological applications. Here, we present Irida-Silicene (ISi), a novel 2D silicon allotrope inspired by Irida-Graphene (IG), which was recently proposed and is entirely composed of carbon atoms. ISi exhibits a buckled structure composed of 3-6-8 membered rings, unlike its planar carbon counterpart. Using density functional theory (DFT) calculations, we discuss its stability, structural, electronic, optical, and mechanical properties. Our results indicate that ISi exhibits bond lengths ranging from 2.27 to 2.32 Å, with buckling of 0.78 Å, the latter significantly larger than that reported for silicene. The nanomaterial demonstrates good dynamical and thermal stability at room temperature, without phonon dispersion with imaginary frequencies, and a cohesive energy of -4.98 eV/atom. ISi is a metallic monolayer with a Dirac cone above the Fermi level in the center of the band, and it is also a nonmagnetic material. Furthermore, the system displays anisotropic electronic properties, showing semiconducting behavior depending on the direction, with a region devoid of electronic states between -0.2 and -0.8 eV. The optical activity of ISi is primarily observed in the infrared and ultraviolet regions, with a peak for photons with an energy of 5.5 eV in the latter case. Finally, regarding mechanical properties, we report estimated elastic and bulk moduli of approximately 34 and 41 N/m, respectively. The system can withstand up to 15% of strain, depending on the direction and type of deformation. These findings suggest that ISi holds potential for various technological applications, expanding the potential uses of 2D silicon-based materials beyond silicene.