Finite-length calculations ofηand phase diagrams of quantum spin chains

This is the authors' abstract. We don't add key points for this paper.

We present a novel means of calculating the exponent {η} for massless phases of quantum spin chains based on Luck's formula. Convergence is illustrated by comparison to exact results for spin 1/2, and the method is used to estimate phase boundaries of the spin-1 chain with single-site and exchange anisotropy. Clear evidence is found in favor of a fluctuation-induced gap for the isotropic antiferromagnet. We elucidate the transition between two different planar phases at large negative D.