Figure 3
From: Topologically protected localised states in spin chains
Energy spectrum of N = 101 spin chains with site 0 (a) weakly, and (b) strongly coupled. The bottom panel represents a zoom of the lower energy band for case (a). In both cases each band state is two-fold degenerate. In case (a) one single localised state sits in the middle, and case (b) three degenerate states sit at zero energy, with a further state above the upper band and one below the lower band.
