We consider an expansion of the ground state wavefunction of quantum lattice many-body systems in a basis whose states are tensor products of block-spin wavefunctions. We demonstrate by applying the method to the antiferromagnetic spin-1/2 chain that by selecting the most important many-body states the technique affords a severe truncation of the Hilbert space while maintaining high accuracy.
@article{arxiv.cond-mat/9706308,
title = {Block-Spin Approach to Electron Correlations},
author = {P. Monthoux},
journal= {arXiv preprint arXiv:cond-mat/9706308},
year = {2009}
}