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TT: Fachverband Tiefe Temperaturen
TT 50: Superconductivity: Theory II
TT 50.7: Vortrag
Mittwoch, 20. März 2024, 16:45–17:00, H 3005
Ab initio calculations of superconducting transition temperatures beyond GW-RPA — •Camilla Pellegrini1, Carl Kukkonen2, and Antonio Sanna1 — 1Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany — 233841 Mercator Isle, Dana Point, California 92629, USA
In ab initio calculations of superconducting properties, the Coulomb repulsion is accounted for at the GW level [1,2] and is usually computed in the random phase approximation (RPA), which neglects vertex corrections both at the polarizability level and in the self-energy. Although this approach is unjustified, the brute force inclusion of higher-order self-energy corrections is computationally prohibitive.
We propose a generalized GW self-energy, where vertex corrections are incorporated into W by employing the Kukkonen and Overhauser (KO) ansatz for the effective interaction between two electrons in the electron gas [3]. By computing the KO interaction in the adiabatic local density approximation, and using it in the Eliashberg equations, we find that vertex corrections lead to a systematic decrease of the critical temperature (Tc), ranging from a few percent in bulk lead to more than 40
[1] C. Pellegrini, R. Heid, A. Sanna, J. Phys. Mater. 5 (2022) 024007
[2] A. Sanna, C. Pellegrini, E.K.U. Gross, Phys. Rev. Lett. 125 (2020) 057001
[3] C. Pellegrini, C. Kukkonen, A. Sanna, Phys. Rev. B 108 (2023) 064511
Keywords: Ab initio methods for superconductivity; Eliashberg equations; GW-RPA; Kukkonen-Overhauser interaction; Density functional theory