  We report on the development of a new shell-model Monte Carlo algorithm which
uses the proton-neutron formalism. Shell model Monte Carlo methods, within the
isospin formulation, have been successfully used in large-scale shell-model
calculations. Motivation for this work is to extend the feasibility of these
methods to shell-model studies involving non-identical proton and neutron
valence spaces. We show the viability of the new approach with some test
results. Finally, we use a realistic nucleon-nucleon interaction in the model
space described by (1p_1/2,0g_9/2) proton and
(1d_5/2,2s_1/2,1d_3/2,0g_7/2,0h_11/2) neutron orbitals above the Sr-88 core to
calculate ground-state energies, binding energies, B(E2) strengths, and to
study pairing properties of the even-even 90-104 Zr and 92-106 Mo isotope
chains.
