Zusammenfassung

Monte Carlo simulations based on the Trotter-Suzuki transformation were carried out using 6×6 and 12×12 lattices and the single-band Hubbard model with intermediaterange repulsive interaction. The absence of the ldquominus-sign problemrdquo for sufficiently low temperatures and appropriate doping indicates bosonic behavior reminiscent of superconductivity. It was found that holes prefer to pair on next-nearest-neighbor sites while nearest neighbors are suppressed.