Perturbation Approach to the Polaron Self-Energy in the Intermediate Coupling Range
Phys. Rev. 137, A1902 – Published 15 March, 1965
DOI: https://doi.org/10.1103/PhysRev.137.A1902
Abstract
By using a diagram technique, it is shown that the polaron energy can be expanded in electron-recoil terms. Together with the common expansion in powers of the coupling constant, a double series is obtained in which many cancellations occur. A subseries is isolated which gives the Lee-Low-Pines (L.L.P.) result in the intermediate coupling range. This subseries can be seen to consist of partial contributions of a certain class of perturbation diagrams. This answers the question put by Pines as to which perturbation diagrams contribute to the L.L.P. result.