SSH model: topological phase with protected edge states
Winding number: 0 | Gap: 0.00
The Su-Schrieffer-Heeger (SSH) model is the simplest 1D topological insulator. It has two hopping amplitudes: t1 (intracell) and t2 (intercell). When t2>t1, the Zak phase is π (winding number W=1) and protected zero-energy edge states appear at the chain ends. The bulk-boundary correspondence guarantees these edge states are robust to perturbations that preserve the chiral symmetry.