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arXiv · 1405.1774

Single polaron properties for double-well electron-phonon coupling

Clemens P. J. Adolphs·Mona Berciu
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Abstract

We show that in crystals where light ions are symmetrically intercalated between heavy ions, the electron-phonon coupling for carriers located at the light sites cannot be described by a Holstein model. We introduce the double-well electron-phonon coupling model to describe the most interesting parameter regime in such systems, and study it in the single carrier limit using the momentum average approximation. For sufficiently strong coupling, a small polaron with a robust phonon cloud appears at low energies. While some of its properties are similar to those of a Holstein polaron, we highlight some crucial differences. These prove that the physics of the double-well electron-phonon coupling model cannot be reproduced with a linear Holstein model.

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Clemens P. J. Adolphs, Mona Berciu. 2014-05-07. Single polaron properties for double-well electron-phonon coupling. https://doi.org/10.1103/physrevb.89.035122

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