Key points are not available for this paper at this time.
We study the disordered Heisenberg spin chain, which exhibits many-body localization at strong disorder, in the weak to moderate disorder regime. A continued fraction calculation of dynamical correlations is devised, using a variational extrapolation of recurrents. Good convergence for the infinite chain limit is shown. We find that the local spin correlations decay at long times as Ct^-, whereas the conductivity exhibits a low-frequency power law ^. The exponents depict subdiffusive behavior 0 at all finite disorders and convergence to the scaling result +2=1 at large disorders.
Khait et al. (Fri,) studied this question.