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 a(0), c(0), and cell volume V-0 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 Theta(D), and hardness H of MoS2 are also obtained successfully. It is found that they all increase monotonically with the increasing pressure.