Effect of pressure on elastic, mechanical and electronic properties of WSe2: A first-principles study

Effect of pressure on elastic, mechanical and electronic properties of WSe2 has been investigated using the first-principles calculations. The calculated lattice parameters, band structure and elastic constants of WSe2 at 0 GPa are in good agreement with the available experimental and calculational values. With the increasing pressure, the lattice parameters and volume of WSe2 decrease whereas the total enthalpy increases. The bulk modulus, Youngʹs modulus and Poissonʹs ratio of WSe2 increase with the increasing pressure, except for a sharp decrease at the pressure of 40 GPa. WSe2 under pressure has larger shear modulus and higher hardness than WSe2 at 0 GPa. With the increase of pressure, the covalent bonding between Se and W atoms in the slabs is enhanced whereas the distance of the stacked slabs is decreased. Additionally, an isostructural semiconductor-semimetal phase transition of WSe2 is found to take place at 40 GPa, which is consistent with the experimental observations.