TI-polaron

A TI-polaron (translation-invariant polaron) is a type of elementary quasiparticle in solid-state physics. The ground state of TI-polaron is a delocalized state of electron-phonon system: the probabilities of electron's occurrence at any point of a space are similar. Both the electron density and the amplitudes of phonon modes (renormalized by an interaction with the electron) are delocalized. The concept of a polaron potential well (formed by local phonons) in which the electron is localized, i.e. self-trapped state is lacking. Accordingly, the induced polarization charge of the translation-invariant polaron is equal to zero.

The ground state energy of the translation-invariant polaron is lower than that of Pekar polaron and is E0 = -0.125720 α2 [1] (for Pekar polaron E0 = -0.10851128 α2), where α is electron-phonon coupling.

TI-polarons can create bound TI-bipolaron states, which play an important role in the theory of superconductivity.[2]

References
  1. V.D. Lakhno. Pekar's ansatz and the strong coupling problem in polaron theory. Phys. Usp., 2015, Vol.58, P.295–308. DOI: 10.3367/UFNr.0185.201503d.0317
  2. V.D. Lakhno. Superconducting properties of 3D low-density TI-bipolaron gas. preprint, 2015, arXiv:1507.08510.
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