Dynamical correlations in one-dimensional charge-transfer insulators

The single-particle spectral function and the density response of a two ban d Emery model for CuO chains is calculated for large on-site Cu repulsion U and large on-sire energy difference Delta. For U much greater thanU-Delta much greater thant the eigenfunctions are products of charge and spin parts , which allows analytical calculation of spectral functions in that limit. For other parameters numerical diagonalization is used. The low-energy hole carriers are shown to be the one-dimensional analogs of the Zhang-Rice sin glets. The validity of the one-band model is discussed. The results are rel evant to the interpretation of photoemission and electron-energy-loss spect roscopy experiments on SrCuO2 and Sr2CuO3.