Monatomic chain, infinite

The system we wish to investigate consists of a single atom a interacting with a semi-infinite monatomic chain. The site (bond) energy of the chain is a( ), while that of the a-atom is aa (fja). Initially, the substrate is represented by a cyclic chain of N atoms, whose GF is given by (2.49). A semi-infinite chain is then formed by breaking the bond between the n = 0 and N — 1 atoms (Fig. 3.1). 

We now specify the substrate to be an infinite cyclic monatomic chain with site (bond) energy a (/l) (see Fig. 8.1(a)). The GF matrix elements are (App. 

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