Electronic structure of the misfit layer compound : band-structure calculations and photoelectron spectra

In order to understand the electronic structure of the misfit layer compound (LaS)(1.14)NbS2 we carried out an ab initio band-structure calculation in a supercell approximation. The band structure is compared with that of the components NbS2 and LaS. The calculations show that the electronic structure of (LaS)(1.14)NbS2 can be regarded as that of LaS intercalated into the host NbS2. There is a transfer of about 0.7 electrons per Nb atom from the LaS to the NbS2 layers; some electrons remain in La 5d orbitals. The states at the Fermi level are dominated by Nb 4d(z)2 orbitals; there are about 0.3 holes per Nb atom. The dispersion of the energy bands shows a large anisotropy. The dispersion bf energy bands for the LaS subsystem is very small along the incommensurate direction. X-ray and ultraviolet photoelectron spectra obtained for the core level electrons and the valence bands are in good agreement with the band-structure calculations.