Elastic Properties and Electronic Structure of WS2 under Pressure from First-principles Calculations

The influence of pressure on the elastic and mechanical properties of the hexagonal transition- metal dichalcogenide WS2 is investigated using the first- principles calculations. With the increase in pressure, the lattice parameters and the volume of WS2 decrease, which is exactly in agreement with the available experimental data and other calculated results. The elastic constants C-ij, bulk modulus B, shear modulus G, Young's modulus E, and Poisson's ratio sigma of WS2 also increase with pressure. At last, for the first time, the band gaps of energy, the partial density of states, and the total density of states under three different pressures are obtained and analysed. It is found that the band gap of WS2 decreases from 0.843 to 0eV when the external pressure varies from 0 to 20 GPa, which implies that WS2 may transform from semiconductors to semimetal phase at a pressure about 20 GPa.