Dimensionality Effects on the Su-Schrieffer-Heeger Model

TL;DR

This study investigates how the dimensionality of the Su-Schrieffer-Heeger model affects electron behavior, revealing significant mass enhancement and spectral changes in different regimes, with polaron formation favored in two dimensions.

Contribution

It provides a diagrammatic analysis of the dimension-dependent SSH model, highlighting new features in electron spectral functions across regimes, especially in 2D.

Findings

Electrons are good quasiparticles in the antiadiabatic limit.

Mass enhancement and spectral weight loss occur at larger e-ph couplings.

Polaronic states are more likely to form in two dimensions.

Abstract

A low order diagrammatic study of the dimension dependent Su-Schrieffer-Heeger model Hamiltonian in the weak electron-phonon coupling regime is presented. Exact computation of both the charge carrier effective mass and the electron spectral function shows that electrons are good quasiparticles in the antiadiabatic limit but new features emerge in the adiabatic and intermediate regime, where the phonons and the electrons compare on the energy scale. Here we find: i) a sizeable mass enhancement over the bare band value, ii) the appearance of many transition peaks in the band bottom spectral function together with a growing loss of spectral weight at larger {\it e-ph} couplings. The onset of a polaronic state is favoured in two dimensions.