  We develop a classical Monte Carlo algorithm based on a quasi-classical
approximation for a pseudospin S=1 Hamiltonian in real space to construct a
phase diagram of a model cuprate with a high Tc. A model description takes into
account both local and nonlocal correlations, Heisenberg spin-exchange
interaction, correlated single-particle, and two-particle transport. We
formulate a state selection algorithm for a given parameterization of the wave
function in order to ensure a uniform distribution of states in the phase
space. The simulation results show a qualitative agreement with the
experimental phase diagrams.
