Datensatz

Zusammenfassung

Using first-principles calculations, we investigate the electronic, mechanical, and optical properties of monolayer WTe₂. Atomic structure and ground state properties of monolayer WTe₂ (T_d phase) are anisotropic which are in contrast to similar monolayer crystals of transition metal dichalcogenides, such as MoS₂, WS₂, MoSe₂, WSe₂, and MoTe₂, which crystallize in the H-phase. We find that the Poisson ratio and the in-plane stiffness is direction dependent due to the symmetry breaking induced by the dimerization of the W atoms along one of the lattice directions of the compound. Since the semimetallic behavior of the T_d phase originates from this W-W interaction (along the a crystallographic direction), tensile strain along the dimer direction leads to a semimetal to semiconductor transition after 1% strain. By solving the Bethe-Salpeter equation on top of single shot G₀W₀ calculations, we predict that the absorption spectrum of T_d-WTe₂ monolayer is strongly direction dependent and tunable by tensile strain.