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Title
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Strong-coupling analysis of large bipolarons in 2 and 3 dimensions
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Author
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Abstract
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| In the limit of strong electron-phonon coupling, we use either a Pekar-type or an oscillator wave function for the center-of-mass coordinate and either a Coulomb or an oscillator wave function for the relative coordinate, and are able to reproduce all the results from the literature for the large-bipolaron binding energy. Lower bounds are constructed for the critical ratio eta(c) of dielectric constants below which bipolarons can exist. It is found that, in the strong-coupling limit, the stability region for bipolaron formation is much larger in two dimensions (2D) than in 3D. We introduce a model that combines the averaging of the relative coordinate over the asymptotically best wave function with a path-integral treatment of the center-of-mass motion. The stability region for bipolaron formation is increased compared with the full path-integral treatment at large values of the coupling constant alpha. The critical values are alpha(c) almost-equal-to 9.3 in 3D and alpha(c) almost-equal-to 4.5 in 2D. Phase diagrams for the presented models are also obtained in both 2D and 3D. |
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Language
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English
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Source (journal)
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Physical review : B : condensed matter. - New York, N.Y., 1978 - 1997
Physical review : B : condensed matter and materials physics. - Lancaster, Pa, 1998 - 2015
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Publication
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New York, N.Y.
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1992
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ISSN
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0163-1829
[print]
1095-3795
[online]
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DOI
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10.1103/PHYSREVB.45.5262
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Volume/pages
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45
:10
(1992)
, p. 5262-5269
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ISI
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A1992HJ68900016
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Full text (Publisher's DOI)
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Full text (open access)
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