DMRG study of a 1D ionic SSH-Hubbard model for Charge-transfer salt

By a DMRG method, we investigate the quantum phase transition in 1D half-filling SSH-Hubbard model with an alternating periodic potential (V) at the anti-adiabatic limit. This model is relevant to the ferroelectric perovskites and organic mixed-stack donor-acceptor crystals. First we confirm the existence of a spontaneous BOW phase at a vanishing e-p coupling. Then at U=0, we find a suppression of the BOW due to quantum phonon fluctuations and the transition point from a BOW phase to a CDW phase occurs at a much lower value of the ionic potential V.