arXiv:cond-mat/0508227 · Physical Review B
Effect of quantum lattice fluctuations on the Peierls broken-symmetry ground state
William Barford, Robert J. Bursill
Abstract
We use the density matrix renormalization group method to investigate the role of gapless, dispersive quantized phonons on the Peierls transition in the extended Hubbard-Peierls model. We calculate the staggered phonon order parameter as a function of the Coulomb interaction and the phonon frequency. For all parameter ranges we show that the staggered phonon order parameter scales as $\sqrt{\ensuremath{\lambda}}$ (and the dimerized bond order scales as $\ensuremath{\lambda}$) as $\ensuremath{\lambda}\ensuremath{\rightarrow}0$ (where $\ensuremath{\lambda}$ is the electron-phonon interaction). We also show that the quantum phonon predictions for the bond order follow the classical (adiabatic) predictions as a function of inverse chain size for small $\ensuremath{\lambda}$. We thus conclude that quantum fluctuations in the nuclear degrees of freedom do not destroy the Peierls state for this model.