First principles calculation of the valence band offsets for \b{eta}-   polytype of A3B6 layered crystals
  The valence band offsets (VBO) for the \b{eta}-type A3B6 layered compounds depending on the thickness of the crystals have been investigated from the first principles, based on the density functional theory. To simulate the structure of a given thickness the periodic slab model was used. Two adjacent crystal slabs consisting of several layers were separated by a vacuum region of two-layer width. It is shown that at the crystal thickness more than 12 layers, photothreshold practically becomes independent on the thickness of the crystal. 
Z.A.Jahangirli, F.M. Hashimzade, D.A. Huseynova, B.H. Mehdiyev, and   N.B. Mustafayev
cond-mat.mtrl-sci