Recent progress in the truncated Lanczos method : application to   hole-doped spin ladders
  The truncated Lanczos method using a variational scheme based on Hilbert space reduction as well as a local basis change is re-examined. The energy is extrapolated as a power law function of the Hamiltonian variance. This systematic extrapolation procedure is tested quantitatively on the two-leg t-J ladder with two holes. For this purpose, we have carried out calculations of the spin gap and of the pair dispersion up to size 2x15. 
O. Chiappa, S. Capponi, D. Poilblanc