Exchange and correlation contributions to superconducting electron pairing

Abstract

The screening of the electron-phonon and Coulomb interactions in an electron gas is considered with use of various forms of the exchange correction term G(q). A solution of the Eliashberg equations including G(q) is achieved with conventional approximations, and the resulting superconducting transition temperatures Tc are found to be very sensitive to the form of exchange. Smooth functional forms of G(g), such as the Hubbard model, yield only small deviations from the random-phase approximation, which greatly overestimates Tc for simple metals such as Na and Li. However, an exchange function with a peak near q≊2kF (e.g., the forms proposed by Devreese and independently by Overhauser) greatly reduces Tc and may explain the mysterious absence of superconductivity in simple metals such as Na, Li, and Rb. These many-body effects may also be significant in superconductors with more complex energy-band structures.

Source-reported materials — not catalogue approval

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