Phonon Overlaps: Polyacetylene, Polarons, and Molecular Size

TL;DR

This paper develops a theoretical framework to understand how polarons and phonons influence electron tunneling in conducting polymers, combining models and DFT calculations to analyze suppression effects and spectral features.

Contribution

It introduces a combined theoretical approach using SSH model and DFT to study phonon and polaron effects on electron tunneling in polymers.

Findings

Phonons and polarons suppress ground-state electron tunneling.

Side-band positions and intensities are quantitatively predicted.

Theoretical results align with experimental observations on molecular quantum dots.

Abstract

We provide a theory for the effects of polarons and phonons in mediating and suppressing the quantum tunneling of electrons into single molecules of conducting polymers, motivated by experiments on molecular quantum dots. The effects of both phonons and excitations of the polaron particle-in-a-box excitations are calculated. Using both the Su-Schrieffer-Heeger (SSH) model of polyacetylene and direct density-functional theory (DFT) calculations, we calculate the suppression of ground--state to ground--state transitions and the position and strength of the side-bands.