Transport in dimerized and frustrated spin systems
  We analyze the Drude weight for both spin and thermal transport of one-dimensional spin-1/2 systems by means of exact diagonalization at finite temperatures. While the Drude weights are non-zero for finite systems, we find indications of a vanishing of the Drude weights in the thermodynamic limit for non-integrable models implying normal transport behavior. 
F. Heidrich-Meisner, A. Honecker, D.C. Cabra, and W. Brenig