Current-current correlations in a CuO3 model system -: art. no. 024421

We study a three-band extended Hubbard model on a CuO3 system by the density-matrix renormalization group method. Our system has geometry similar to that of a section of the CuO2 plane of the copper-oxide superconductors. We have studied the effects of nearest-neighbor repulsions on the current-current correlations of two model CuO3 systems. We have calculated several types of staggered current correlations as a function of various model parameters such as interaction strengths and filling. We show that repulsive interactions are clearly capable of increasing the magnitude of the current-current correlations in both models studied. The long-distance behavior of the current-current correlations is qualitatively influenced by V. We show that repulsive interactions are capable of enhancing correlations involving at least one copper-oxygen rung over distances comparable to the length of the system. In some cases, V decreases the exponent corresponding to the power-law decay, leading to a considerable slowing down of the long-distance decay of the current-current correlations, compared to that of the Hubbard model.