Title: POLARONS BY THE NONLOCAL DYNAMICAL COHERENT POTENTIAL METHOD
Authors: S.V.Izvekov (T.Shevchenko Kyiv University, Department of Physics, 6 Glushkov Av., UA-252022 Kyiv, Ukraine)

The nonlocal dynamical coherent potential approximation (NDCPA) is formulated to calculate a single-electron (exciton) Green's function of polaron due to the interaction of an electron (exciton) with phonons with dispersion. This approximation is an extension of the dynamical CPA. The NDCPA provides an efficient means of calculating an approximate Green's function for a dynamical model of electrons (excitons) strongly coupled to optical or acoustical phonons, in the entire ranges of the electron (exciton)-phonon coupling strengths and electron (exciton) transfer. The electron (exciton)-phonon coupling in the Hamiltonian may involve terms of any order with respect to phonon operators. A set of recurrent equations is derived in the case of a system at zero temperatures, from which the coherent potential can be obtained as a function of energy E. The simple algorithm for the polaron spectra calculations is obtained for a linear electron (exciton)-phonon coupling in the antiadiabatic limit.

Comments: Figs. 0, Refs. 31, Tabs. 0.