Range-separated multideterminant density-functional theory with a short-range correlation functional of the on-top pair density.

We introduce an approximation to the short-range correlation energy functional with multideterminantal reference involved in a variant of range-separated density-functional theory. This approximation is a local functional of the density, the density gradient, and the on-top pair density, which locally interpolates between the standard Perdew-Burke-Ernzerhof correlation functional at a vanishing range-separation parameter and the known exact asymptotic expansion at a large range-separation parameter. When combined with (selected) configuration-interaction calculations for the long-range wave function, this approximation gives accurate dissociation energy curves of the H2, Li2, and Be2 molecules and thus appears as a promising way to accurately account for static correlation in range-separated density-functional theory.