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Localization, conductivity, and superconductivity
Author(s) -
Larsson Sven,
Klimkāns Agris
Publication year - 2000
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/1097-461x(2000)80:4/5<713::aid-qua21>3.0.co;2-1
Subject(s) - delocalized electron , condensed matter physics , superconductivity , anderson localization , mott insulator , valence (chemistry) , ground state , physics , hubbard model , chemistry , band gap , excited state , quantum mechanics
Electron localization is of great importance for the understanding of phonon coupling in ordinary conductivity and superconductivity. We discuss localization in “Mott insulators,” but take a critical view on the Mott model, which explains localization on the basis of a disproportionation reaction, involving the Mott–Hubbard parameter U . Instead we emphasize electron–nuclear interactions in determining localization properties. Depending on the ratio between intersite coupling and reorganization energy, the nature of valence‐state fluctuations range from localized, discrete hops between sites to delocalized transport, either barrierless hopping or phonon‐coupled band motion. In the case of three stable oxidation states, there is a possibility for a conducting ground state with a finite energy gap to excited states. Finally we discuss the appearance of “giant magnetoresistance” as an example of delocalized mixed valence system in the metallic and ferromagnetic phase. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 80: 713–720, 2000