Path Integral Description of a Semiclassical Su-Schrieffer-Heeger Model

TL;DR

This paper employs a path integral approach to analyze a semiclassical Su-Schrieffer-Heeger model, revealing thermodynamic behaviors and a glassy-like low-temperature heat capacity anomaly due to electron hopping dynamics.

Contribution

It introduces a path integral formalism for the SSH model with arbitrary electron-phonon coupling, enabling analysis of thermodynamic properties across temperatures.

Findings

Identified a low-temperature upturn in heat capacity over temperature ratio.

Derived a non-local source action for electron-phonon interactions.

Analyzed thermodynamic properties from 1K to room temperature.

Abstract

The electron motion along a chain is described by a continuum version of the Su-Schrieffer-Heeger Hamiltonian in which phonon fields and electronic coordinates are mapped onto the time scale. The path integral formalism allows us to derive the non local source action for the particle interacting with the oscillators bath. The method can be applied for any value of the {\it e-ph} coupling. The path integral dependence on the model parameters has been analysed by computing the partition function and some thermodynamical properties from $T= 1K$ up to room temperature. A peculiar upturn in the low temperature {\it heat capacity over temperature} ratio (pointing to a glassy like behavior) has been ascribed to the time dependent electronic hopping along the chain.