Exploring strain-driven structural and optical responses in twin graphene

We carried out studies on how compressive uniaxial strain affects the structural and optical properties of twin graphene (TG), with the lattice constant serving as a variable. By applying strains ranging from 2% to 10% in steps of 2%, we were able to systematically explore the changes brought about by compression. The analysis involved calculating the real and imaginary parts of the dielectric function, along with the absorption coefficient, reflectivity, and refractive index, for TG in both strained and unstrained states. The results showed that compressive strain reduces the energy bandgap, yet the material retains its semiconducting nature even at a strain of 10%. We also examined the optical properties of TG in two specific polarizations: in-plane ([Formula: see text]-direction) and out-of-plane ([Formula: see text]-direction). In the in-plane direction, key parameters like the dielectric function, reflectivity, and refractive index improved significantly under strain, especially in the infrared and visible light ranges. On the other hand, the out-of-plane direction exhibited stronger responses in the ultraviolet (UV) and deep UV ranges, where the absorption coefficient peaked. These results highlight how versatile and adaptable the optical properties of TG are, making it an excellent candidate for applications across the infrared, visible, and UV spectral ranges.