QUANTUM MONTE-CARLO STUDY OF THE ONE-DIMENSIONAL HUBBARD-MODEL WITH RANDOM HOPPING AND RANDOM POTENTIALS

We have studied the effects of random-hopping matrix elements and random potentials on the properties of the one-dimensional Hubbard model. Using a quantum Monte Carlo technique, disorder-averaged static spin- and charge-density susceptibilities have been evaluated for various strengths of the disorder. Results for the spin susceptibility at wave number q = 2k(F) indicate that this quantity, which is the fastest diverging susceptibility of the pure system, diverges as T --> 0 also when there is randomness in the hopping matrix elements, but not in the presence of random potentials. Both types of disorder cause a divergence of the uniform magnetic susceptibility. However, for random potentials a finite critical strength of the disorder appears to be required. At half-filling the transition from Mott (gapped) to Anderson (gapless) insulating behavior has been studied. A critical disorder strength is needed to destroy the gap, in agreement with Ma's renormalization group calculations.