An optimized phonon approach for the numerical diagonalization of interacting electron-phonon systems is proposed. The variational method is based on an expansion in coherent states that leads to a dramatic truncation in the phonon space. The reliability of the approach is demonstrated for the extended Holstein model showing that different types of lattice distortions are present at intermediate electron-phonon couplings as observed in strongly correlated systems. The connection with the density matrix renormalization group is discussed.
@article{arxiv.cond-mat/0407445,
title = {A variational approach to the optimized phonon technique for electron-phonon problems},
author = {V. Cataudella and G. De Filippis and F. Martone and C. A. Perroni},
journal= {arXiv preprint arXiv:cond-mat/0407445},
year = {2009}
}