I will present two recently developed approaches accelerating multideterminant wave-function calculations by combination with a density-functional approximation, with the aim of efficiently describing strongly correlated molecular systems.

1) The combination of a long-range selected configuration-interaction (sCI) wave function with a short-range correlation functional of the density and the on-top pair density [1].

2) The combination of a standard sCI wave function with a correlation density functional correcting for the incompleteness of the one-electron basis set [2].

I will also indicate what the remaining mathematical and computational challenges are.

References

[1] A. Ferté, E. Giner, J. Toulouse, Range-separated multideterminant density-functional theory with a short-range correlation functional of the on-top pair density, Journal of Chemical Physics 150, 084103 1-10 (2019).

[2] E. Giner, B. Pradines, A. Ferté, R. Assaraf, A. Savin, J. Toulouse, Curing basis-set convergence of wave-function theory using density-functional theory: A systematically improvable approach, Journal of Chemical Physics 149, 194301 1-15 (2018).