Comment on `Dynamical properties of small polarons'

TL;DR

This paper critiques a recent claim that standard small polaron theory breaks down, clarifying that proper interpretation aligns theory with numerical results and highlighting issues in linking correlation functions to electron hopping.

Contribution

The authors correct the interpretation of small polaron theory and demonstrate its consistency with numerical results, challenging recent claims of theory breakdown.

Findings

Proper interpretation aligns small polaron theory with numerical results.

Incorrect interpretation led to false claims of theory failure.

Connecting correlation functions to electron hopping was unsuccessful.

Abstract

We show that the conclusion on the breakdown of the standard small polaron theory made recently by E.V. deMello and J. Ranninger (Phys. Rev. B 55, 14872 (1997)) is a result of an incorrect interpretation of the electronic and vibronic energy levels of the two-site Holstein model. The small polaron theory, when properly applied, agrees well with the numerical results of these authors. Also we show that their attempt to connect the properties of the calculated correlation functions with the features of the intersite electron hopping is unsuccessful.