The Gross-Neveu Model with Chemical Potential; An Effective Theory for Solitonic-Metallic Phase Transition in Polyacetylene?

TL;DR

This paper models the phase transition in doped polyacetylene using the Gross-Neveu model with chemical potential, revealing a first-order phase transition that explains abrupt changes in electrical properties.

Contribution

It introduces a novel application of the Gross-Neveu model with chemical potential to describe solitonic-metallic phase transition in polyacetylene, including finite density effects and phase transition analysis.

Findings

Identifies a first-order phase transition at critical dopant concentration.

Calculates the critical dopant concentration including next-to-leading order corrections.

Explains sharp rise in electric conductivity and Pauli paramagnetism in doped polyacetylene.

Abstract

The Gross-Neveu model with chemical potential is investigated as a low-energy effective theory of polyacetylene. In particular, we focus on the abrupt change in the features of electric conductivity such as sharp rise in the Pauli paramagnetism at dopant concentration of about 6%. We will try to explain it by the finite density phase transition in the Gross-Neveu model. The thermodynamic Bethe ansatz is combined with the large-N expansion to construct thermodynamics of the Gross-Neveu model. A first-order phase transition is found in leading order in the 1/N expansion and it appears to be stable against the 1/N correction. The next to leading order correction to the critical dopant concentration is explicitly calculated.