Band structure of the Jahn-Teller polaron from Quantum Monte Carlo

TL;DR

This paper develops a Quantum Monte Carlo method to accurately analyze the band structure and properties of the Jahn-Teller polaron, revealing similarities to the Holstein polaron and detailed spectral features.

Contribution

It introduces a path-integral formulation and exact diagrammatic Quantum Monte Carlo approach for the Jahn-Teller polaron, enabling precise calculations of its properties.

Findings

JTP band structure similar to Holstein polaron

Mass increases exponentially with coupling

Spectrum becomes flat at large momenta at low phonon frequencies

Abstract

A path-integral representation is constructed for the Jahn-Teller polaron (JTP). It leads to a perturbation series that can be summed exactly by the diagrammatic Quantum Monte Carlo technique. The ground-state energy, effective mass, spectrum and density of states of the three-dimensional JTP are calculated with no systematic errors. The band structure of JTP interacting with dispersionless phonons, is found to be similar to that of the Holstein polaron. The mass of JTP increases exponentially with the coupling constant. At small phonon frequencies, the spectrum of JTP is flat at large momenta, which leads to a strongly distorted density of states with a massive peak at the top of the band.