Electronic properties of a semi-infinite ionic crystal chain

Electronic properties of a semi-infinite linear chain of an ionic crystal, simulated by assigning s and p orbitals on alternate sites, have been studied by using the Green's-function method. We obtain the same results for the energy and the decay constant of the surface states as those obtained by using the linear-combination-of-atomic-orbitals (LCAO) method. The Green's-function method also allows us to study the properties of the bulk states which show severe modifications owing to the presence of the surface. In particular, we show that the bulk local densities of states develop strong oscillatory behavior and that there exist certain Bragg-like conditions at which both the real and the imaginary part of the local Green's function go to zero.