INCOMMENSURATE CHARGE-DENSITY-WAVE INSTABILITY IN THE EXTENDED 3-BANDHUBBARD-MODEL

The infinite-U three-band Hubbard model is considered in order to desc ribe the CuO2 planes of the high-temperature superconducting cuprates. The charge instabilities are investigated when the model is extended with a nearest-neighbor repulsion between holes an copper d and oxygen p orbitals and in the presence of a long-range Coulombic repulsion. I t is found that a first-order valence instability line ending with a c ritical point is present as in the previously investigated model witho ut long-range forces. However, the dominant critical Instability is th e formation of incommensurate charge-density waves, which always occur before the valence-instability critical point is reached, An effectiv e singular attraction arises in the proximity of the charge-density wa ve instability, accounting for both a strong pairing mechanism and for the anomalous normal-state properties. [S0163-1829(98)00607-9].