Advancing anisotropic Migdal-Eliashberg calculations with ab-initio Coulomb interactions and intermediate representation basis

Recently, we successfully introduced the intermediate representation (IR) basis functions into the computational scheme of the anisotropic Migdal-Eliashberg equations in the EPW code [1], significantly reducing the computational cost for summing over Matsubara frequencies without loss in accuracy [2]. This computational advancement enables us to account for both the electron-phonon and Coulomb interactions on equal footing. By employing the Coulomb interaction obtained from the inverse dielectric matrix within the random-phase approximation, we compute the superconducting gap functions and critical temperatures for several representative materials. In this presentation, we will assess the predictive power of our methodology and compare the calculated transition temperatures with those from the ab-initio density functional theory for superconductors and experiments.



[1] H. Lee, S. Poncé, K. Bushick et al., npj Comput. Mater. 9, 156 (2023).

[2] H. Mori, T. Nomoto, R. Arita, and E. R. Margine, Phys. Rev. B. 110, 064505 (2024).