Electronic structure of the misfit-layer compound (SnS)1.17NbS2deduced from band-structure calculations and photoelectron spectra

In order to understand the electronic structure of the misfit-layer compound (SnS${)}_{1.17}$ ${\mathrm{NbS}}_2$ we carried out an ab initio band-structure calculation of the closely related commensurate compound (SnS${)}_{1.20}$ ${\mathrm{NbS}}_2$. The band structure is compared with calculations for ${\mathrm{NbS}}_2$ and for hypothetical SnS with structure and interatomic distances as in (SnS${)}_{1.20}$ ${\mathrm{NbS}}_2$. The calculations show that the electronic structure is approximately a superposition of the electronic structures of the two components ${\mathrm{NbS}}_2$ and SnS, with a small charge transfer from the SnS layer to the ${\mathrm{NbS}}_2$ layer. The interlayer bonding between SnS and ${\mathrm{NbS}}_2$ is dominated by covalent interactions. X-ray and ultraviolet photoelectron spectra were obtained for the valence bands. The observed spectra are in good agreement with the band-structure calculations.