One of the most fundamental drawbacks of conventional wave function methods is the slow convergence of energies and properties with respect to the one-electron basis set.
As proposed by Kutzelnigg more than thirty years ago, one can introduce explicitly the interelectronic distance $r_{12}$ to significantly speed up the convergence.
However, significant computational overheads are introduced by the large auxiliary basis used to resolve three- and four-electron integrals.
In this Letter, we describe a drastically different approach which combines density-functional theory (DFT) and wave function methods.
The present universal, density-based basis set incompleteness correction, which can be applied to any wave function method, relies on short-range correlation density functionals from range-separated DFT to estimate the basis set incompleteness error.
Our results clearly demonstrate that the present basis set correction recovers quintuple-$\zeta$ quality atomization and correlation energies with triple-$\zeta$ basis sets for a much cheaper computational cost compared to explicitly-correlated F12 methods.
Because of the large impact of our work, we expect it to be of interest to a wide audience within the chemistry community and beyond.
