Accurate Electron-phonon Interactions from Advanced Density Functional Theory

Electron-phonon coupling (EPC) is key for understanding superconductivity, resistivity and other properties of materials. Although first-principles-based EPC calculations using density functional theory (DFT) are used widely, their accuracy and efficiency is limited by the employed exchange-correlation approximations. This problem is exacerbated in complex d-electron materials, which are typically thought to require beyond-DFT methods or empirical corrections such as the Hubbard U. Here, we show that the r²SCAN meta-GGA density functional can correctly capture strong EPC effects in transition-metal oxides such as CoO and NiO, without requiring the introduction of empirical parameters. We can thus expect r²SCAN to also achieve high accuracy in modeling phonon-mediated superconducting properties of the main group compounds (e.g., MgB₂). Our study showcases the ability of r²SCAN to extend the scope of accurate EPC calculations to encompass complex d-electron materials.