  The ground state phase diagram of the one-dimensional Bose-Fermi Hubbard
model is studied in the canonical ensemble using a quantum Monte Carlo method.
We focus on the case where both species have half filling in order to maximize
the pairing correlations between the bosons and the fermions. In case of equal
hopping we distinguish between phase separation, a Luttinger liquid phase and a
phase characterized by strong singlet pairing between the species. True
long-range density waves exist with unequal hopping amplitudes.
