Numerical study of the effects of disorder on the three-dimensional Hubbard model

The combined effects of interactions and disorder are investigated using a finite temperature quantum Monte Carlo technique for the three-dimensional Hubbard model with random potentials of finite range. The temperature depen dence of the charge compressibility shows that the Mott gap seems to collap se beyond a finite disorder strength. This is a quantum phase transition fr om an incompressible phase to a compressible phase driven by disorder. We c alculate the antiferromagnetic structure factor in the presence of disorder as well. Strong antiferromagnetic correlation, which is characteristic of the Mott insulator, is destroyed by the presence of a finite amount of diso rder.