Realistic description of electron-energy-loss spectroscopy for one-dimensional Sr₂CuO₃

We investigate the electron-energy-loss spectrum of one-dimensional undoped CuO₃ chains within an extended multiband Hubbard model and an extended one-band Hubbard model, using the standard Lanczos algorithm. Short-range intersite Coulomb interactions are explicitly included in these models, and long-range interactions are treated in the random-phase approximation. The results for the multiband model with standard parameter values agree very well with experimental spectra of Sr₂CuO₃. In particular, the width of the main structure is correctly reproduced for all values of momentum transfer. We find no evidence for enhanced intersite interactions in Sr₂CuO₃.