Exact diagonalization and quantum Monte Carlo study of the spin-1/2 XXZ model on the square lattice - art. no. 214411

The spin-1/2 XXZ model on an infinite square lattice at zero temperature ha s been studied and is presented here. Our methods using finite square latti ces have been the exact diagonalization and quantum Monte Carlo methods. Th e physical properties estimated per lattice vertex include ground-state and first-excited-state energy, staggered magnetization, and susceptibility in the parallel and perpendicular directions, spin stiffness, and spin-wave v elocity. In the XXZ model range from the Ising model to the Heisenberg mode l our estimates of physical properties compare very well with estimates by several other methods published in several other papers. In the XXZ range b etween the Heisenberg and XY models there is very little in the literature to compare with our finite lattice estimates of physical properties.