Dynamics in the one-dimensional extended ionic Hubbard model

Abstract

We investigate single-particle spectral densities and dynamical charge and spin structurefactors of the one-dimensional extended ionic Hubbard model in the band insulator regimeby using the perturbative continuous unitary transformations method. The one-bodystaggered potential is considered as the unperturbed part and the hopping term, on-siteelectron–electron interaction, and the nearest-neighbor repulsive interaction are treated asthe perturbations. The excitation spectrum of this model was determined in aprevious work (Hafez and Jafari 2010 Eur. Phys. J. B 78 323). It was shown thatwhen the intersite interaction is off, there are two antibound state modes and onebound state mode in the singlet channel and two bound state modes in the tripletchannel, while for finite values of intersite interaction two bound state modes werefound in each channel. Our results for dynamical charge and spin structure factorsindicate that only one of two bound/antibound state modes can be probed byelectron-energy-loss spectroscopy and inelastic neutron scattering experiments.