Condensed Matter Physics, 2009, vol. 12, No. 4, pp. 665675
DOI:10.5488/CMP.12.4.665
Title:
Method of intermediate problems in the Fröhlich polaron model
Author(s):

A.V. Soldatov
(V.A. Steklov Mathematical Institute, Department of Mechanics, 8 Gubkina Str., 119991 Moscow, Russia)

Method of intermediate problems in the theory of linear semibounded selfadjoint operators on rigged Hilbert space was applied to the investigation of the ground state energy of the Fröhlich polaron model. It was shown that various infinite sequences of nondecreasing improvable lower bound estimates for the polaron ground state energy can be derived for arbitrary values of the electronphonon interaction constant. The proposed approach allows for explicit numerical evaluation of the thus obtained lower bound estimates at all orders and can be straightforwardly generalized for investigation of the lowlying branch of the slowmoving polaron excitation energy spectral curve adjacent to the ground state energy of the polaron at rest. In conjunction with numerous, already derived by multitudinous methods, wellknown upper bound estimates for the energy spectral curve of the Fröhlich polaron as a function of the electronphonon interaction constant and the polaron total momentum, the aforesaid improvable lower bound estimates might provide one with virtually precise magnitude for the energy of the slowmoving polaron.
Key words:
polaron, Fröhlich polaron model, lower bound estimates,
method of intermediate problems, ground state energy
PACS:
71.38.k, 71.38.Fp
