Nature of the Peierls- to Mott-insulator transition in 1D

TL;DR

This paper investigates the transition from Peierls to Mott insulators in a 1D model, revealing how electron-phonon and electron-electron interactions influence the nature of the phase change.

Contribution

It provides a detailed numerical analysis of the crossover between Peierls and Mott insulators in the 1D Holstein-Hubbard model, highlighting the transition's dependence on interaction strengths.

Findings

Transition can be first order or continuous depending on parameters.

Intermediate phase with finite gaps exists during the transition.

Transition relates to the ionic Hubbard model in the adiabatic limit.

Abstract

In order to clarify the physics of the crossover from a Peierls band insulator to a correlated Mott-Hubbard insulator, we analyze ground-state and spectral properties of the one-dimensional half-filled Holstein-Hubbard model using quasi-exact numerical techniques. In the adiabatic limit the transition is connected to the band to Mott insulator transition of the ionic Hubbard model. Depending on the strengths of the electron-phonon coupling and the Hubbard interaction the transition is either first order or evolves continuously across an intermediate phase with finite spin, charge, and optical excitation gaps.