Particle Path Correlations in a Phonon Bath

TL;DR

This paper uses path integral methods to analyze a particle in a phonon bath, revealing temperature-dependent correlations and a low-temperature heat capacity upturn indicative of glassy behavior.

Contribution

It introduces a novel application of path integral formalism to a generalized SSH model, capturing particle-phonon correlations and their effects on thermodynamic properties.

Findings

Electronic correlations vary with temperature.

Low temperature heat capacity shows a glassy-like upturn.

Particle path influences phonon subsystem behavior.

Abstract

The path integral formalism is applied to derive the full partition function of a generalized Su-Schrieffer-Heeger Hamiltonian describing a particle motion in a bath of oscillators. The electronic correlations are computed versus temperature for some choices of oscillators energies. We study the perturbing effect of a time averaged particle path on the phonon subsystem deriving the relevant temperature dependent cumulant corrections to the harmonic partition function and free energy. The method has been applied to compute the total heat capacity up to room temeperature: a low temperature upturn in the heat capacity over temperature ratio points to a glassy like behavior ascribable to a time dependent electronic hopping with variable range in the linear chain.