Ab initio study of MoS2 and Li adsorbed on the (10(1)over-bar-0) face of MoS2

Periodic Hartree-Fock methods were used to calculate the geometric and elec tronic properties of 2H-MoS2, 1T-MoS2, the (10(1) over bar 0) surface of Mo S2 and Li adsorbed thereon. For the calculations, the structures were gener ated by an extension of unit cells to the respective bulk structures (1T- a nd 2H-MoS2) or by cutting sections, each consisting of six or eight layers of sulfur and molybdenum, from a crystal ((10(1) over bar 0) surface of MoS 2 with and without adsorbed Li). Structural optimization was performed with a post Hartree-Fock DFT correlation correction. The calculated structures of 2H-MoS2 and 1T-MoS2 are in good agreement with experimental data and the metastable and metallic properties of 1T-MoS2 are also described correctly . The relaxation of the (10(1) over bar 0) surface of 2H-MoS2 leads to a mi nor reconstruction of the surface accompanied by the formation of S-2 speci es and an inward relaxation of Mo atoms. Adsorption of Li on this surface i s favoured in the high symmetry positions above the van der Waals gap. Rela xation of the Li-covered (10(1) over bar 0) surface of 2H-MoS2 shifts the L i atoms towards the S-2 pairs and closer to the surface. Upon adsorption, t he system becomes metallic and delocalized surface states form at the Fermi level due to electron transfer processes from the Li atoms to the surface layers of MoS2.