DMRG analysis of the SDW-CDW crossover region in the 1D half-filled Hubbard-Holstein model

TL;DR

This paper uses DMRG to study the transition between SDW and CDW phases in a 1D Hubbard-Holstein model, revealing an intermediate metallic phase in the weak-coupling regime.

Contribution

It provides a detailed analysis of the SDW-CDW crossover in the 1D Hubbard-Holstein model, highlighting the existence of an intervening metallic phase.

Findings

Confirmation of an expanded SDW-CDW transition region

Identification of an intervening metallic phase

Analysis of correlation exponents and excitation gaps

Abstract

In order to clarify the physics of the crossover from a spin-density-wave (SDW) Mott insulator to a charge-density-wave (CDW) Peierls insulator in one-dimensional (1D) systems, we investigate the Hubbard-Holstein Hamiltonian at half filling within a density matrix renormalisation group (DMRG) approach. Determining the spin and charge correlation exponents, the momentum distribution function, and various excitation gaps, we confirm that an intervening metallic phase expands the SDW-CDW transition in the weak-coupling regime.