Mo₆S₆ nanowires: structural, mechanical and electronic properties

Abstract.

The properties of $\ensuremath{\mathrm{ Mo_6S_6 }}$ nanowires were investigated with ab initio calculations based on the density-functional theory. The molecules build weakly coupled one-dimensional chains, like $\ensuremath{\mathrm{ Mo_6Se_6 }}$ and Mo₆S_9-xI_x, and the crystals are strongly uniaxial in their mechanical and electronic properties. The calculated moduli of elasticity and resilience along the chain axis are c₁₁ = 320 GPa and E_R = 0.53 GPa, respectively. The electronic band structure and optical conductivity indicate that the $\ensuremath{\mathrm{ Mo_6S_6 }}$ crystals are good quasi-one-dimensional conductors. The frequency-dependent complex dielectric tensor ε, calculated in the random-phase approximation, shows a strong Drude peak in ε_∥, i.e., for the electric field polarised parallel to the chain axis, and several peaks related to interband transitions. The electron energy loss spectrum is weakly anisotropic and has a strong peak at the plasma frequency ħω_p ≈20 eV. The stability analysis shows that $\ensuremath{\mathrm{ Mo_6S_6 }}$ is metastable against the formation of the layered $\ensuremath{\mathrm{ MoS_2 }}$.