The amplitudes of the occupied state of the SSH model. Red and orange lines show the first and second components of the occupied state in Eq. (21). (a), (b) Under reality condition. The occupied state is anti-periodic for (a) t = 0.7 whereas it is periodic for (b) t = 1.3. (c) In a smooth complex gauge with φ_v(k) = k/2. Both the real and imaginary parts are smooth for |t| < 1. Figures are adopted from the supplemental materials in Ref. [7].