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Início
Agenda |
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- 18 de outubro de 2017
16h30
Sala
18 (Cristalografia) -
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Hai
Guoqiang
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IFSC
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Electron
pairing in crystal: from metastable electron pair to bipolaron
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Considering the shell structure and significant
correlation in electron pairs in atoms, we distinguish the
exchange-correlation effects between two electrons of opposite
spins occupying the same orbital from the average correlation
among many electrons in the crystal. In the periodic potential
of a crystal with lattice constant larger than the effective
Bohr radius of the valence electrons, these correlated electron
pairs may form a metastable energy band above the corresponding
single-electron band with an energy gap. In order to stabilize
these metastable electron pairs, we calculate the many-electron
exchange-correlation renormalization and polaron correction to
the two-band system with single electrons and electron pairs.
The calculations indicate that the electron-phonon interaction
is essential to counterbalance the Coulomb repulsion to
stabilize the electron pairs. The interplay of the
electron-electron and electron-phonon interactions leads to part
of the electrons form stable electron pairs (bipolarons) sitting
on the Fermi surface of the single-electron band.
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