Fig. 4.

Spectra of examples belonging to classes BDI ($\gamma =0$) and D (trivial) ($\gamma \ne 0$). (Left) The band structure of the periodic BDI model given in Eq. 21. (Middle) Spectrum of the open D model. The parity of the winding number is even; therefore, the topological edge modes are not protected upon turning on $\gamma \ne 0$. (Right) The band structure of the D model for $\gamma =1$. Parameters chosen to obtain the figures are: $t=2\hspace{0.17em}{\text{Hz}}^2$, $t\prime =10\hspace{0.17em}{\text{Hz}}^2$, $s=4\hspace{0.17em}{\text{Hz}}^2$, $s\prime =8\hspace{0.17em}{\text{Hz}}^2$, and $\mu =14\hspace{0.17em}{\text{Hz}}^2$.