Pekar's Ansatz and the Strong Coupling Problem in Polaron Theory

TL;DR

This paper examines a translation-invariant polaron theory that surpasses Pekar's ansatz in accuracy, providing improved energy estimates and insights into bipolaron stability without relying on traditional approximations.

Contribution

It introduces a translation-invariant approach to polaron theory that yields lower energy values and better stability parameters than Pekar's ansatz.

Findings

Polaron energy is lower than Pekar's prediction.

Provides optimal values for bipolaron coupling energy.

Discusses physical implications of translation-invariant polarons.

Abstract

A detailed consideration is given to the translation-invariant theory of Tulub polaron constructed without the use of Pekar ansatz. A fundamental result of the theory is that the value of the polaron energy is lower than that obtained on the basis of Pekar ansatz which was considered as an asymptotically exact solution in the strong coupling limit. In the case of bipolarons the theory yields the best values of the coupling energy and critical parameters of their stability. Numerous physical consequences of the existence of translation-invariant polarons and bipolarons are discussed.