The Peierls-Hubbard model at weak coupling

TL;DR

This paper studies how electron-electron interactions influence the Peierls transition in a one-dimensional model, revealing a critical coupling value where interactions switch from enhancing to suppressing lattice dimerization.

Contribution

It provides a perturbative analysis of the Peierls-Hubbard model at weak coupling, identifying a critical electron-lattice coupling constant affecting dimerization.

Findings

Hubbard interaction can either enhance or suppress dimerization depending on coupling strength.

A critical coupling value g_c = 0.689348 is identified where the Hubbard interaction switches from enhancement to suppression.

Second order perturbation theory is used to determine the critical point.

Abstract

We investigate the Peierls transition in the one-dimensional Peierls-Hubbard model at half filling in the adiabatic approximation for the lattice. Depending on the value of the electron-lattice coupling constant g the equilibrium dimerization can be either enhanced or suppressed by the Hubbard interaction U. Applying second order perturbation theory we determine the critical value g_c = 0.689348 below which the Hubbard interaction enhances the dimerization.