Ground state features of the Frohlich model

TL;DR

This paper introduces a new variational wave function for the Frohlich model that improves estimates of the polaron ground state energy across all coupling strengths, aligning well with existing results.

Contribution

It proposes a novel variational wave function for the Frohlich model that outperforms the Feynman path integral approach in estimating the polaron ground state energy.

Findings

Better ground state energy estimates than Feynman method

Accurate calculations of phonon number and energies

Good agreement with existing results

Abstract

Following the ideas behind the Feynman approach, a variational wave function is proposed for the Fr\"ohlich model. It is shown that it provides, for any value of the electron-phonon coupling constant, an estimate of the polaron ground state energy better than the Feynman method based on path integrals. The mean number of phonons, the average electronic kinetic and interaction energies, the ground state spectral weight and the electron-lattice correlation function are calculated and successfully compared with the best available results.