Effective one-band models for the one-dimensional cuprate Ba2 −xSrxCuO3 +δ

We consider a multiband Hubbard model H_m for Cu and O orbitals in Ba_{2 −x}Sr_xCuO_{3 +δ} similar to the three-band model for two-dimensional cuprates. The hopping parameters are obtained from maximally localized Wannier functions derived from ab initio calculations. Using the cell perturbation method, we derive both a generalized t -J model H_{t J} and a one-band Hubbard model H_H to describe the low-energy physics of the system. H_{t J} has the advantage of having a smaller relevant Hilbert space, facilitating numerical calculations, while additional terms should be included in H_H to accurately describe the multiband physics of H_m. Using H_{t J} and the density matrix renormalization group method, we calculate the wave-vector-resolved photoemission and discuss the relevant features in comparison with recent experiments. In agreement with previous calculations, we find that the addition of an attractive nearest-neighbor interaction of the order of the nearest-neighbor hopping shifts the weight from the 3 k_F to the holon-folding branch. Kinetic effects also contribute to this process.