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Hindered rotators by off-site ions in solids: Optical conductivity by sombrero potentials

I. Polyanski·A. G. Andreev·V. Krastev·M. Mladenova·M. Georgiev
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Abstract

We consider the optical conductivity of carriers scattered by local sombrero potentials associated with hindered planar rotators in solids. Examples for hindered rotators are provided by off-center substitutional Li ions in colored alkali halides and off-site apical oxygens O(A) in layered perovskites. We obtain off-center displacements by solving for the vibronic mixing of electronic states at the displacing ion site. The eigenvalue equation of a hindered rotator is solved in 2D by Mathieu's periodic functions, as the rotation is quantized in rotational bands. We discuss the optical conductivities pertaining to each of the exemplified cases.

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I. Polyanski, A. G. Andreev, V. Krastev, M. Mladenova, M. Georgiev. 2007-01-26. Hindered rotators by off-site ions in solids: Optical conductivity by sombrero potentials. https://arxiv.org/abs/cond-mat/0701673

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