Fig. 3: Properties of a half-filled SSHH model with OBC.
From: Topological phases of a dimerized Fermi–Hubbard model for semiconductor nano-lattices
a Eigenenergy spectrum in the strongly correlated regime (U = 10), colored according to the spin ∣Sz∣ of the eigenstates (states with ±Sz have the same energy). For each value of Sz up to 60 lowest energies are shown. The ground-state degeneracy χ changes from one to four at the topological phase transition due to the four degenerate edge states. b Eigenenergy spectrum in the non-trivial phase (Δt = 0.5) as a function of the on-site interaction. The ground-state degeneracy reduces from χ = 6 in the non-interacting regime to χ = 4 in the interacting regime due to the raising in energy of two ionic states where the edge is double occupied (see text). c The entanglement entropy between the first subsystem consisting of the two ends and the second one consisting of the remaining sites in the middle of the chain. d Spin correlation \(\left\langle {S}_{z,j}{S}_{z,k}\right\rangle\) in the non-trivial phase. The abscissa and ordinate are the sites j and k. The bulk dimers have perfect AFM correlation but the edges are uncorrelated with the rest; e same as d for Δt = 0 showing long-range AFM correlation; and f same as e for Δt = −0.5.
