We describe a new, biased Monte Carlo scheme to determine the crystal struc
tures of zeolites from powder diffraction data. We test the method on all p
ublicly known zeolite materials, with success in all cases. We show that th
e method of parallel tempering is a powerful supplement to the biased Monte
Carlo. (C) 1999 American Institute of Physics. [S0021-9606(99)50503-5].