Predicting Irida-Silicene:\nA Novel 2D Silicon Allotrope

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