The XXZ Heisenberg model describes interacting quantum spins on a 1D lattice: H = Σ [J(SᵢˣSⱼˣ + SᵢʸSⱼʸ) + ΔSᵢᶻSⱼᶻ] − h·Σ Sᶻ. The anisotropy Δ controls the quantum phase: gapless XY phase (|Δ|<1), Néel order (Δ>1), and ferromagnet (Δ<−1). Visualizes classical Monte Carlo spin configurations and energy landscape.