Two Dimensional Hubbard Model with Off-Diagonal Disorder

The two dimensional Hubbard model with randomness in the hopping elements is investigated in the half filled band case. We employ a finite temperature Quantum Monte Carlo method which has no ``minus sign problem'' for this type of disorder at half filling due to the conservation of particle-hole symmetry. We study the disorder induced formation of local moments, the break-down of antiferromagnetic long range order, and from the electronic compressibility the closing of the charge gap. The connection to doped semiconductors close to the metal-insulator transition is discussed.