  We studied the superfluid-to-Mott insulator transition for bosonic hard
spheres loaded in asymmetric three-dimensional optical lattices by means of
diffusion Monte Carlo calculations. The onset of the transition was monitored
through the change in the chemical potential around the density corresponding
to one particle per potential well. With this method, we were able to reproduce
the results given in the literature for three-dimensional symmetric lattices
and for systems whose asymmetry makes them equivalent to a set of quasi-one
dimensional tubes. The location of the same transition for asymmetric systems
akin to a stack of quasi-two dimensional lattices will be also given. Our
results were checked against those given by a Bose-Hubbard model for similar
arrangements.
