Spin-correlation functions of theS=1Heisenberg-Ising chain by the large-cluster-decomposition Monte Carlo method

We study the spin-correlation functions of the one-dimensional S=1 antiferromagnetic Heisenberg-Ising model by the large-cluster-decomposition Monte Carlo method. It is found that this model shows a second-order transition at the anisotropy parameter λc=1.167±{}0.007. The obtained critical exponents ({η}=0.253±{}0.002, {β}=0.126±{}0.007, {ν}=0.98±{}0.02) strongly suggest that this transition belongs to the same universality class as the two-dimensional Ising model.