Critical Dopant Concentration in Polyacetylene and Phase Diagram from a Continuous Four-Fermi Model

TL;DR

This paper uses an advanced perturbation theory method to evaluate the critical dopant concentration in polyacetylene, improving upon previous models by including finite N effects and analyzing temperature influences.

Contribution

It applies the Optimized Perturbation Theory to a four-Fermi model for polyacetylene, providing more accurate predictions of critical dopant levels beyond mean field approximations.

Findings

Critical dopant concentration matches experimental data.

Finite N effects significantly influence the results.

Thermal effects have minimal impact at laboratory temperatures.

Abstract

The Optimized Perturbation Theory (OPT) method, at finite temperature and finite chemical potential, is applied to the field theory model for polyacetylene. The critical dopant concentration in trans-polyacetylene is evaluated and compared with the available experimental data and with previous calculations. The results obtained within the OPT go beyond the standard mean field (or large-N) approximation (MFA) by explicitly including finite N effects. A critical analysis of the possible theoretical prescriptions to implement and interpret these corrections to the mean field results, given the available data, is given. For typical temperatures probed in the laboratory, our results show that the critical dopant concentration is only weakly affected by thermal effects.