The $E\otimes e$ Jahn-Teller Polaron in Comparison with the Holstein Polaron

TL;DR

This paper compares the Jahn-Teller and Holstein polarons, revealing how symmetry affects vertex corrections, effective mass, and polaron crossover, with exact and analytical results in different coupling regimes.

Contribution

It provides a detailed comparison of Jahn-Teller and Holstein polarons, highlighting the impact of symmetry on vertex corrections and polaron properties, including exact and analytical results.

Findings

Vertex correction less effective for Jahn-Teller polaron

Smaller effective mass for Jahn-Teller polaron

Different large-to-small polaron crossover behavior

Abstract

Based on an exact expression for the self-energy of the Jahn-Teller polaron, we find that symmetry of pseudospin rotation makes the vertex correction much less effective than that for the Holstein polaron. This ineffectiveness brings about a smaller effective mass m^* and a quantitatively differenent large-to-small polaron crossover, as examined by exact diagonalization in a two-site system. In the strong-coupling and antiadiabatic region, a rigorous analytic expression is found for m^*.