Abstract
We present the derivation of an ab initio and parameter-free effective electron-electron interaction that goes beyond the screened random phase approximation and accounts for superconducting pairing driven by spin fluctuations. The construction is based on many-body perturbation theory and relies on the approximation of the exchange-correlation part of the electronic self-energy within time-dependent density functional theory. This effective interaction is included in an exchange-correlation kernel for superconducting density functional theory in order to achieve a completely parameter free superconducting gap equation. First results from applying the new functional to a simplified two-band electron gas model are consistent with experiments.
Highlights
In the last 30 y the field of superconductivity has been revolutionized by the discovery of high-temperature superconductivity (SC)
The second goal we aim for is to cast this effective interaction along the standard Coulomb and phonon contribution [10] in a functional that can be used within the ab initio SCDFT framework
In this work we have derived a fully ab initio effective electron-electron interaction containing the effect of a pairing mediated by SF
Summary
In the last 30 y the field of superconductivity has been revolutionized by the discovery of high-temperature (hi-Tc) superconductivity (SC). In particular we aim to include the effect of low-energy spin fluctuations in a computationally feasible way and completely ab initio (i.e., without the use of parameters, like a Stoner exchange splitting). The second goal we aim for is to cast this effective interaction along the standard Coulomb and phonon contribution [10] in a functional that can be used within the ab initio SCDFT framework. This self-energy may be used in many-body theory but the focus of this work lies on SCDFT and in Sec. V a functional is derived using the Sham-Schluter connection. In the last part of the present work (Sec. VI) the functional is applied to a two-band model system and the trends with respect to the Coulomb, phonon and spin-fluctuation (SF) contributions are investigated
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