Condensed Matter Physics, 1995, No. 5, p. 161-191, English
Title: Effective local anharmonic potentials in solids. A model approach
Authors: I.V. Stasyuk, Yu.V. Sizonenko

The role of electron-phonon interaction in the formation of local anharmonic lattice potentials in crystal is investigated on the basis of the simple model. The case of three particle ion cluster $A-B-A$ is considered. The interaction of the electron subsystem with the vibrational modes $u_r$ and $u_{ir}$, being Raman and infrared-active respectively, is taken into account. The calculation of effective ion potentials and distribution functions is performed. The possibility of realization of one $(u_r^0,0)$ or two $({u'}_r^0,\pm u_{ir}^0)$ equilibrium positions of cluster at various values of the theory parameters, electron concentration and temperature is discussed. The "phase" diagrams are built for the description of possible states of the cluster and of the corresponding topological types of effective potentials. The energy spectrum of the model is analyzed. It is shown, that the quazipolaron effect leads to the formation of doublet in the low frequency range. The sublevel distance is defined by the electron-transfer parameter renormalized due to electron-phonon coupling.

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