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DF: Dielektrische Festkörper
DF 7: Poster
DF 7.14: Poster
Thursday, March 30, 2000, 09:30–13:00, C
Self-trapped electron states in a chain with two vibrational modes — •L. Brizhik1, K. Dichtel2 und A. Eremko1 — 1Bogolyubov Institute for Theoretical Physics, Metrologichna Str., 14b, 03143, Kyiv, Ukraine — 2Instititut für Theoretische Physik und Astrophysik, Universität Kiel
We study a molecular chain, described by the Froehlich Hamiltonian, taking into account electron interaction with both acoustic and optical phonons in the nonadiabatic case. Possible material applications are binary chains like copper-oxygen or conjugated polymers. Generally there are three types of solutions: small polaron, almost free and self-trapped states of charge carriers, depending on the values of the coupling constants and the other parameters [1]. We report the influence of the presence of both modes on the parametric diagrams, calculated using a variational method. It is shown that the region of the parameters corresponding to the self-trapped state is much broader as compared with the one-mode model. This result supports the validity of soliton and large polaron pictures in a much wider class of low-dimensional materials, whose parameters in the one-mode model would not correspond formally to the region of a soliton-type electron ground state. In the case of a material with parameters close to the crossover between the regions of different ground states, the account of more realistic phonon structure is necessary to describe correctly the transport and optical properties.
1. L.S. Brizhik, K. Dichtel, A.A. Eremko, J. Supercond., 12 (1999) 239.