Início
Agenda 

 18 de outubro de 2017
16h30 Sala
18 (Cristalografia) 

Hai
Guoqiang

IFSC


Electron
pairing in crystal: from metastable electron pair to bipolaron


Considering the shell structure and significant
correlation in electron pairs in atoms, we distinguish the
exchangecorrelation 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
singleelectron band with an energy gap. In order to stabilize
these metastable electron pairs, we calculate the manyelectron
exchangecorrelation renormalization and polaron correction to
the twoband system with single electrons and electron pairs.
The calculations indicate that the electronphonon interaction
is essential to counterbalance the Coulomb repulsion to
stabilize the electron pairs. The interplay of the
electronelectron and electronphonon interactions leads to part
of the electrons form stable electron pairs (bipolarons) sitting
on the Fermi surface of the singleelectron band.



