For one defect these equations lead to where is only a small perturbation to , at least for not too large, playing the role of an additional phaseshift. Therefore the eigenmomenta remain real and do not lead to localization effects.
Figure illustrates the change of the band structure due to our defects.
There we have plotted the single particle levels vs. their quantum numbers . It is an interesting feature of our defects that they do not lead to a level splitting, but to a flattening of the band at , indicating the cut of sites for . This flattening will be important for the understanding of the phase sensitivity calculated in section .