ELECTRONIC-STRUCTURE OF THE MISFIT-LAYER COMPOUND (SNS)(1.17)NBS2 DEDUCED FROM BAND-STRUCTURE CALCULATIONS AND PHOTOELECTRON-SPECTRA

In order to understand the electronic structure of the misfit-layer compound (SnS)(1.17)NbS2 we carried out an ab initio band-structure calculation of the closely related commensurate compound (SnS)(1.20)NbS2. The band structure is compared with calculations for NbS2 and for hypothetical SnS with structure and interatomic distances as in(SnS)(120)NbS2. The calculations show that the electronic structure is approximately a superposition of the electronic structures of the two components NbS2 and SnS, with a small charge transfer from the SnS layer to the NbS2 layer. The interlayer bonding between SnS and NbS2 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.