Continuum limit of bipartite lattices: The Su-Schrieffer-Heeger model
Phys. Rev. B 112, 205419 – Published 17 November, 2025
DOI: https://doi.org/10.1103/j12q-6bhm
Abstract
We present a continuous nonlocal model that faithfully replicates the rich topological and spectral features of the Su-Schrieffer-Heeger (SSH) model. Remarkably, our model shares the SSH models' bulk energy spectrum, eigenstates, and Zak phase—hallmarks of its topological character—while introducing a tunable length-scale quantifying nonlocality. This parameter allows for a controlled interpolation between nonlocal and local regimes. Furthermore, for a specific value of the exact spectral equivalence to the discrete SSH model is established. Distinct from previous continuous analogs based on Schrödinger or Dirac-type Hamiltonians, our approach maintains chiral symmetry, does not require an external potential, and features periodic energy bands. On finite domains, the model supports a flat band with zero energy formed by a countable infinite set of exponentially localized zero-energy edge states of topological origin. Beyond SSH, our method lays the foundation for constructing nonlocal, continuous analogs of a wide class of bipartite and multipartite lattices, opening paths for theoretical exploration and challenges for experimental realization in topological quantum matter.