Near-Basis-Set-LimitDouble-Hybrid DFT Energies withExceptionally Low Computational Costs

The use of density-based basis-set correction (DBBSC) [J. Phys. Chem. Lett. 2019, 10, 2931] is extended to double-hybrid (DH) functionals. The proposed DBBSC-DH approach significantly reduces the basis-set requirements for accurate calculations, enabling near-basis-set-limit results using affordable one-electron basis sets. The accuracy of this method is comparable to that of the recently proposed DH functionals utilizing explicitly correlated (F12) second-order perturbation theory contribution [J. Phys. Chem. Lett. 2022, 13, 9332]; however, its computational costs and resource demands are only a fraction of those associated with the DH-F12 scheme. Applications to real-life examples reveal that only a 30% overhead in wall-clock time is observed compared to conventional DH calculations, demonstrating that the DBBSC-DH approach is a compelling alternative to the excellent but relatively costly DH-F12 functionals, particularly for extended molecular systems.