Phase diagram of the spin-Peierls chain with local coupling
  We explore the ground-state phase diagram of a Heisenberg spin chain coupled locally to optical phonons (bond coupling), using large-scale density matrix renormalization group calculations and an extended perturbative analysis. For the quantum phase transition from the spin liquid to the dimerized phase, we find deviations from previous quantum Monte Carlo and flow equation results. 
Alexander Weisse, Georg Hager, Alan R. Bishop, Holger Fehske