J. Mizia, ELECTRONIC PAIRING MECHANISM DUE TO BAND MODIFICATION WITH INCREASINGPAIR NUMBER, Physica status solidi. b, Basic research, 191(2), 1995, pp. 479-485
It is shown that a shift of an electron band with electron occupation
number n, which is changing during the transition to the superconducti
ng state, can lower the total energy of the system. In fact it will br
ing a negative contribution to the pairing potential, which is proport
ional to the product of the electron band shift with occupation number
and the charge transfer during the transition to the superconducting
state. The shift of the electron band comes from the change of stresse
s and the change of correlation effects in the CuO2 plane with n, that
in turn is caused by the changing oxygen concentration. This model ex
plains the phenomenological success of Hirsch's model, which gives no
explanation how the band shift in energy can give rise to superconduct
ivity.