First-principles study of electronic and elastic properties of hexagonal layered crystal MoS₂ under pressure

The structural, electronic, and elastic properties of hexagonal layered crystal MoS₂ under pressure are investigated using first-principles calculations within the local density approximation (LDA). The calculated lattice parameters a₀, c₀, and cell volume V₀ of MoS₂ are in good agreement with the available experimental data. Our calculations show that MoS₂ is an indirect band gap semiconductor and there is a vanishing anisotropy in the rate of structural change at around 25 GPa, which is consistent with the experimental result. We also analyse the partial density of states (PDOS) of MoS₂ at 0 and 14 GPa, which indicate that the whole valence bands of MoS₂ are mainly composed by the Mo-4d and S-3s states at 0 GPa, while they are mainly composed by the Mo-4p, Mo-4d, and S-3p states at 14 GPa. The electronic charge density difference maps show the covalent characteristic of Mo-S, and the bonding properties of MoS₂ are investigated by using the Mulliken overlap population. In addition, the elastic constants C_ij, bulk modulus B, shear modulus G, Young's modulus Y, the Debye temperature Θ_D, and hardness H of MoS₂ are also obtained successfully. It is found that they all increase monotonically with the increasing pressure.