Vibronic pairwise charge transfer in copper-oxide sheets: A possible approach to high temperature superconductivity theory

Summary

To accommodate the number of holes and fractional number of atoms in doped highT _c superconductors, and to produce a periodic structure with given symmetry, we postulate a quadruple cell with four copper atoms on the CuO₂ layer. The quadruple cell structure hasD _2h symmetry which can be distorted toC _2h geometry underB _1g vibration. Such a structure allows the interconversion of different spin angular momenta into paired spins similar to Cooper pairs. It also provides vibronic interactions that lower the energy of the ground state. For electron (hole) pairing, we construct the running wave Bloch sums consisting of linear combination of bonding/antibonding geminals (instead of one-electron atomic orbitals) in these quadruple cells. For “bond” movement we construct the Bloch sums consisting of linear combination of “Covalon” waves in quadruple cells related to the movement of conjugate (alternating) bonds. In both cases the pair-wise charge (hole/electron) transfer is coupled with antisymmetric vibrations under a double-well potential related to Peierls distortion. The vibronic mixing of different running bonds with different antisymmetric vibrations at various distances, accounts for the different long-range order of charge transfer. Our formulations represent an alternative view of BCS theory, Bisoliton theory and Resonanting Valence Bond theory by using a quantum chemical, position-space approach to a more tight binding situation.