  In this brief report, we show that in a 1D system with unit-cell doubling,
the coefficient of the $\theta$-term is not only determined the topological
index, $\int i\bra{u_k}\frac{\d}{\d k}\ket{u_k}{\rm d}k$. Specifically, the
relative position between the electronic orbitals and the ions also alters the
coefficient. This resolves a paradox when we apply our previous result to the
Su-Shreiffer-Heeger model where the two ground states related by a lattice
translation have $\theta$ differed by $\pi$. We also show that the static
dielectric screening is the same with or without boundaries, on the contrary to
what we have commented in our previous paper.
