Ground state and spectral properties of the doped one-dimensional optical Hubbard-Su-Schrieffer-Heeger model

Electron-phonon (e-p) coupling is believed to have an essential role in the study of many strongly correlated systems. One model that gained recent and wide interest, is the Su-Schrieffer-Heeger (SSH) model, where the atomic motion modulates the atomic hopping integrals. This model has rich and complex physics including light bipolarons and nontrivial topological properties in 1D. The introduction of the Hubbard U opens a door towards studying the interplay of strong correlations with this rich physics. For example, recent studies have found that the half-filled Hubbard SSH model supports Peierls and Mott insulating phases, but the effect of doping on this model remains unclear. Here, we study the ground and excited state properties of the doped 1D Hubbard-SSH model for a range of e-p coupling values using DMRG. In the strong coupling regime, the system tends to dimerize due to an unphysical sign change in the effective hoping, which has a strong signature in the ground state correlation. We also study the effect of phonon frequency by explicitly computing the single particle spectral function for this model.