Transfer-matrix approach for modulated structures with defects

We consider scattering of electrons by defects in a periodically modulated, quasi-one-dimensional structure, nil hin a tight-binding model. Combining a transfer matrix method and a Green function method we derive a formula fo r a Landauer conductance and show its equivalence to the result of Kubo lin ear response theory. We obtain explicitly unperturbed lattice Green functio ns from their equations of motion, using the transfer matrices. We apply th e presented formalism in computations of the conductance of several multiba nd modulated structures with defects: (a) carbon nanotubes (b) two-dimensio nal (2D) superlattice (c) modulated leads with 1D wire in the tunneling reg ime.