Why holes are not like electrons: II. The role of the electron-ion interaction

Phys.Rev.B 71, 104522 (2005), cond-mat/0504013 (Los Alamos)

In recent work ( Phys.Rev. B 65, 184502 (2002) ), we discussed the difference between electrons and holes in energy band in solids from a many-particle point of view, originating in the electron-electron interaction, and argued that it has fundamental consequences for superconductivity. Here we discuss the fact that there is also a fundamental difference between electrons and holes already at the single particle level, arising from the electron-ion interaction. The difference between electrons and holes due to this effect parallels the difference due to electron-electron interactions: holes are more dressed than electrons . We propose that superconductivity originates in 'undressing' of carriers from $both$ electron-electron and electron-ion interactions, and that both aspects of undressing have observable consequences.