Origin of the Coulomb Pseudopotential

Abstract

We address the outstanding problem of electron pairing in the presence of strong Coulomb repulsion at small to moderate values of the Coulomb parameter, $r_s\lesssim 2$, and demonstrate that the pseudopotential framework is fundamentally biased and uncontrolled. Instead, one has to break the net result into two distinctively different effects: the Fermi liquid renormalization factor and the change in the effective low-energy coupling. The latter quantity is shown to behave non-monotonically with an extremum at $r_s\approx 0.75$. Within the random-phase approximation, Coulomb interaction starts to enhance the effective pairing coupling at $r_s>2$, and the suppression of the critical temperature is entirely due to the renormalized Fermi liquid properties. Leading vertex corrections change this picture only quantitatively. Our results call for radical reconsideration of the widely accepted repulsive pseudopotential approach and show the need for precise microscopic treatment of Coulomb interactions in the problem of superconducting instability.

References in corpus (3)

• Charge density waves and electronic properties of superconducting kagome metals
• Discrete Lehmann representation of imaginary time Green's functions
• Revisiting the homogeneous electron gas in pursuit of the properly normed ab initio Eliashberg theory

Cited by in corpus (6)

• Screening Induced Crossover between Phonon- and Plasmon-Mediated Pairing in Layered Superconductors
• Discrete Lehmann representation of three-point functions
• Precursory Cooper Flow in Ultralow-Temperature Superconductors
• Theoretical study of phonon-mediated superconductivity beyond Migdal-Eliashberg approximation and Coulomb pseudopotential
• Self-Consistent Coulomb Interactions from Constrained Dynamical Mean-Field Theory
• Uniform electron benchmark for the first-principles $G{W}_0$-Eliashberg theory