1997/07/18 by A. P. Young · 1 citation
Physics and Astronomy · #cond-mat.dis-nn
paper · pdf · doi:10.1103/physrevb.56.11691
published as Phys. Rev. B56, 11691 (1997) · 10 pages, 14 postscript files included. The discussion of the typical time dependent correlation function has been greatly expanded. Other papers of APY are available on-line at http://schubert.ucsc.edu/peter
arxiv created 1997/07/18 · arxiv updated 2009/11/30
We study numerically the paramagnetic phase of the spin-1/2 random transverse-field Ising chain, using a mapping to non-interacting fermions. We extend our earlier work, Phys. Rev. 53, 8486 (1996), to finite temperatures and to dynamical properties. Our results are consistent with the idea that there are ``Griffiths-McCoy'' singularities in the paramagnetic phase described by a continuously varying exponent z(δ), where δ measures the deviation from criticality. There are some discrepancies between the values of z(δ) obtained from different quantities, but this may be due to corrections to scaling. The average on-site time dependent correlation function decays with a power law in the paramagnetic phase, namely τ-1/z(δ), where τ is imaginary time. However, the typical value decays with a stretched exponential behavior, exp(-cτ1/μ), where μ may be related to z(δ). We also obtain results for the full probability distribution of time dependent correlation functions at different points in the paramagnetic phase.