The translationally invariant polaron theory of Tulub is discussed in detail which makes no use the Pekar's ansatz (believed to provide the asymptotically exact solution in the strong coupling limit) and fundamentally produces a lower-energy polaron than when using the anzatz. In the case of the bipolaron, the theory yields the best values for bonding energy and for critical stability parameters. A variety of physical implications of the existence of translationally invariant polarons and bipolarons are discussed.

Keywords: Froehlich Hamiltonian, Lee—Low—Pines transformation, weak coupling, Bose condensate, F-center PACS: 71.38.−k, 74.20.−z, 74.72.−h (all) DOI: 10.3367/UFNe.0185.201503d.0317 URL: https://ufn.ru/en/articles/2015/3/d/ 000356096100004 2015PhyU...58..295L Citation: Lakhno V D "Pekar's ansatz and the strong coupling problem in polaron theory" Phys. Usp. 58 295–308 (2015) BibTexBibNote ® (generic)BibNote ® (RIS)MedlineRefWorks Received: 29th, November 2013, revised: 10th, December 2014, accepted: 20th, May 2014 Оригинал: Лахно В Д «Анзац Пекара и проблема сильной связи в теории полярона» УФН 185 317–331 (2015); DOI: 10.3367/UFNr.0185.201503d.0317