Electron-phonon couplings within density functional theory and beyond: Methods and application to FeSe
Phys. Rev. B 113, 184521 – Published 28 May, 2026
DOI: https://doi.org/10.1103/f3l8-rktd
Abstract
Semilocal functionals are widely recognized as insufficient for capturing electronic structure of quantum materials due to inadequate treatment of electronic correlations, necessitating beyond-semilocal approaches. However, such beyond-semilocal functionals currently lack a scheme to compute electron-phonon coupling (EPC) accurately and consistently from first-principles. This gap hinders understanding of quantum phenomena like superconductivity in FeSe, leaving its EPC-driven nature debated. Here, we bridge it by developing an atomic-orbital-based framework that delivers full functional consistency across all components of EPC properties, applicable to both semilocal functionals and beyond. Using the Heyd-Scuseria-Ernzerhof (HSE) functional, we successfully predict the superconducting properties of bulk FeSe, including its ambient-pressure behavior and pressure-dependent dome. HSE accurately captures key structural and electronic characteristics, i.e., Se height, band topology, and phonon spectra, and significantly enhances EPC matrix elements, ultimately yielding superconducting transition temperatures close to experiments. Thus, our work not only developed an algorithm to calculate EPC beyond semilocal functional, but also demonstrates the importance of advanced functionals for understanding EPC-driven properties.
