@article{fehske_metallicity_2008, title = {Metallicity in the half-filled {Holstein}-{Hubbard} model}, url = {http://dx.doi.org/10.1209/0295-5075/84/57001}, doi = {10.1209/0295-5075/84/57001}, abstract = {We re-examine the Peierls insulator to Mott insulator transition scenario in the one-dimensional Holstein-Hubbard model where, at half-filling, electron-phonon and electron-electron interactions compete for establishing charge- and spin-density-wave states, respectively. By means of large-scale density-matrix renormalization group calculations we determine the spin, single-particle and two-particle excitation gaps and prove —in the course of a careful finite-size scaling analysis— recent claims for an intervening metallic phase in the weak-coupling regime. We show that for large phonon frequencies the metallic region is even more extended than previously expected, and subdivided into ordinary Luttinger-liquid and bipolaronic-liquid phases.}, journal = {EPL (Europhysics Letters)}, author = {Fehske, H. and Hager, G. and Jeckelmann, E.}, year = {2008}, keywords = {luttinger}, pages = {57001+} }