Quantum Monte Carlo simulation of the one-dimensional spin-S xxz model. II. High precision calculations for S=1/2

For pt.I see ibid., vol.18, p.2479, (1985). A quantum Monte Carlo method developed in the first paper of this series is used to investigate the spin-1/2 isotropic ferromagnet and antiferromagnet. Critical indices are computed in a high precision simulation. The authors obtain alpha =-0.261+or-0.013, gamma =1.552+or-0.008 for the ferromagnet, and alpha =-1.202+or-0.009, gamma =1.132+or-0.012 for the antiferromagnet.