First principles calculations of the Bi₂Te₃ (0001) surface: effect of surface Relaxation

The surface (0001) of the Bi₂Te₃ composite, which is a topological insulator, was investigated using first principles calculations based on Density Functional Theory (DFT). This study examined the effect of surface relaxation on the electronic states of the material, as well as spin-orbit coupling. The results indicate that the allowed energy states crossing at the Fermi level originate from the most exposed Bi₂Te₃ monolayer of the surface, while the innermost layers retain their semiconducting character. It was demonstrated that introducing spin-orbit coupling is necessary to replicate the reported states of Bi₂Te₃. Additionally, structural relaxation plays a crucial role in the surface states and must be taken into account.