2 8 Ju l 1 99 8 Peierls instability and optical response in the one – dimensional half – filled Holstein model of spinless fermions

Peierls instability and optical response in the one–dimensional half–filled Holstein model of spinless fermions Abstract The effects of quantum lattice fluctuations on the Peierls transition are studied within the one–dimensional Holstein molecular crystal model by means of exact diagonalization methods. Applying a very efficient variational Lanczos technique, the ground–state phase diagram is obtained in excellent agreement with predictions of recent density matrix renormalization group calculations. The transition to the charge–density–wave regime is signaled by a strong increase in the charge structure factor. In the metallic regime, the non– universal Luttinger liquid parameters (charge velocity and coupling constant) are deduced from a finite–size scaling analysis. The variational results are supported by a complete numerical solution of the quantum phonon Holstein model on small clusters, which is based on a well–controlled phonon Hilbert space truncation procedure. The metallic and charge–density–wave phases are characterized by significant differences in the calculated optical absorption spectra.