(a) (b) The open-boundary spectra of Hamiltonian  in Eq. (5) and  ¯ in Eq. (5). The parameters are taken to be t 2 = 1 , γ =4/3, and t z = 0.3 . Panels (a₁)–(b₄) show the eigenfunctions. The x-axis is the coordinate of the chain. Panels (a₁)–(a₄) are the non-Hermitian cases. Panels (b₁)–(b₄) are the Hermitian cases. Panels (a₁), (a₂), (b₁), (b₂) show the zero-energy modes of the two chains. Panels (a₃), (a₄), (b₃), (b₄) show the non-zero-energy modes of the two chains.