Quantum Monte Carlo Simulations For The Three-Band Hubbard Model

We present in this article results of Quantum Monte Carlo simulations for the three-band Hubbard model obtained both with the grand canonical approach as well as with theT=0formalism. A direct comparison of Quantum Monte Carlo results with experimental values for the charge-transfer gap leads to a set of parameters for the three-band Hubbard model that consistently describes salient features of the high-Tcsuperconductors. We find long-range antiferromagnetic order in the undoped case as well as an incommensurate structure for a doping concentration ofδ≈0.20. Moreover the magnetic susceptibility as a function of doping δ is in a qualitative agreement with experiments. Concerning dynamical properties, we have evaluated the spectral density$A\left( {\vec k,\,\omega } \right)$. The dispersion of the state with the lowest excitation energy is in very good agreement with experimental photoemission and inverse photoemission experiments for a doping concentration ofδ=0.25. In the superconducting regime, we find that the interaction vertex for the pairing correlation function in the extended s-channel shows a maximum forδ~0.20, resembling the dependence ofTcon doping. This feature is not present for other symmetries of the order parameter or in other parameter regions.