| Issue |
Europhys. Lett.
Volume 42, Number 5, June 1998
|
|
|---|---|---|
| Page(s) | 523 - 528 | |
| Section | Condensed matter: electronic structure, electrical, magnetic and optical properties | |
| DOI | https://doi.org/10.1209/epl/i1998-00283-5 | |
| Published online | 01 September 2002 | |
The small-polaron crossover: Comparison between exact results and vertex correction approximation
1
Dipartimento di Fisica, Università di Roma
“La Sapienza” P.le A. Moro 2, 00185 Roma, Italy
2
Dipartimento di Fisica, Università di L'Aquila
via Vetoio, 67100 Coppito-L'Aquila, Italy and INFM,
Unità di L'Aquila
3
INFM, Unità di Roma 1,
Dipartimento di Fisica, Università di Roma I “La Sapienza”
P.le A. Moro 2, 00185 Roma, Italy
Received:
28
January
1998
Accepted:
8
April
1998
We study the crossover from quasi-free electron to small polaron
in the Holstein model for a single electron
by means of both exact and self-consistent calculations in
one dimension and on an infinite coordination lattice.
We show that the crossover occurs when both strong coupling
(
)
and multiphonon (
) conditions are fulfilled leading to
different relevant coupling constants (λ) in the adiabatic
and (
) antiadiabatic region of the parameters space.
We also show that the self-consistent calculations obtained
by including the first electron-phonon vertex correction give accurate
results in a sizeable region of the phase diagram well separated
from the polaronic crossover.
PACS: 71.38.+i – Polarons and electron-phonon interactions / 63.20.Kr – Phonon-electron and phonon-phonon interactions
© EDP Sciences, 1998
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