The effect of electron-electron interactions on the conditions of   surface state existence
  Electronic surface states in one-dimensional two-band TBA model are studied by use of the Green function method. The local density of states (LDOS) at successive atoms in a semi-infinite chain, even in the case of atoms distant from the surface, is found to be clearly different from that observed in an unperturbed (infinite) chain. The surface atom occupancy is calculated self-consistently, with the effect of electron-electron interactions taken into account. The electron-electron interactions are shown to have a significant impact on the conditions of surface state existence. 
Jaroslaw Klos