Competing orders in the one-dimensional Su-Schrieffer-Heeger model

We study the phase diagram of the one-dimensional spinless Su-Schrieffer-Heeger (SSH) model at half filling as a function of phonon frequency and electron-phonon coupling. In the adiabatic limit of static phonons (vanishing phonon frequency), the ground state is well understood to be a bond-ordered Peierls state that supports topological excitations at domain walls. In the antiadiabatic limit (infinite phonon frequency), the model maps onto the t-V model with a Luttinger liquid phase below and charge-density-wave order above a critical coupling. Using a recently developed directed-loop quantum Monte Carlo method for retarded interactions [1], we study the competition between these orders at finite phonon frequencies.

[1] M. Weber, F. F. Assaad, M. Hohenadler: Phys. Rev. Lett. 119, 097401 (2017)