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JOURNALS // Teoreticheskaya i Matematicheskaya Fizika // Archive

TMF, 1974 Volume 21, Number 3, Pages 415–423 (Mi tmf3909)

This article is cited in 4 papers

Dispersion of the permittivity tensor of ionic crystals in the exciton region

A. F. Lubchenko, V. M. Nitsovich, N. V. Tkach


Abstract: The Bogolyubov–Tyablikov method is used to allow simultaneously for the linear and quadratic terms of the exciton-phonon interaction in a calculation of the two-time retarded temperature Green's function of the excitons. It is shown that in the case of weak exciten-phonon coupling the imaginary part of the permittivity tensor can be described by a function of quasi-Lorentzian type, in which the temperature genesis of the parameters is determined by the linear, $\varphi$, and quadratic, $\Phi$, functions of the exciton-phonon coupling. For the interaction of excitons with high-energy phonons the contribution of $\Phi$ to the mass operator may be overwhelmingly important if $\Phi/\varphi>\varphi/\Omega$, where $\Omega$ is the phonon energy.

Received: 02.01.1974


 English version:
Theoretical and Mathematical Physics, 1974, 21:3, 1244–1249


© Steklov Math. Inst. of RAS, 2025