Abstract
A nonlocal dynamic coherent-potential approximation is formulated as a further development of the dynamic coherent-potential method. The nonlocal dynamic coherent-potential approximation is an efficient method of determining the one-exciton Green’s function in a model with the Hamiltonian in the strong-coupling approximation, where a spectrum of optical phonons is assumed, and the exciton-phonon interaction operator is linear or quadratic in the phonon operators. A system of recursion equations is derived, from which the coherent potential is found as a function of the energy E and the wave vector k. An analytical expression is derived for the one-exciton Green’s function in the case of narrow (in comparison with the phonon energy) exciton bands and exciton-phonon interaction linear in the phonon operators. For broader exciton bands and more complex exciton-phonon interaction the system of equations determining the coherent potential represents a recursion algorithm, which can be effectively implemented by numerical means.
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Fiz. Tverd. Tela (St. Petersburg) 39, 1560–1563 (September 1997)
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Izvekov, S.V. Excitonic polaron in the molecular crystal model: Nonlocal dynamic coherent-potential approximation. Phys. Solid State 39, 1383–1388 (1997). https://doi.org/10.1134/1.1130084
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DOI: https://doi.org/10.1134/1.1130084