A semi-exact study of self-trapping transition in a one-dimensional Holstein-Hubbard model

Abstract

The nature of self-trapping transition in the one-dimensional extended Holstein-Hubbard model is investigated for both adiabatic and anti-adiabatic regimes. The coherence and correlations of the phonons are incorporated accurately by applying a sequence of unitary transformations and a fully-generalized many-phonon wave function is chosen as the averaging phonon state to obtain an effective electronic problem. The renormalized electronic problem is subsequently treated exactly using the method of Bethe ansatz and the self-trapping transition is shown to be continuous over the entire range of the material parameters.