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

## TL;DR

This paper presents a new local approximation for short-range correlation energy in range-separated density-functional theory, improving the accuracy of dissociation energy calculations for small molecules by interpolating between known limits.

## Contribution

It introduces a novel local functional of density, gradient, and on-top pair density that interpolates between established correlation functionals at different range-separation parameters.

## Key findings

- Accurate dissociation energy curves for H2, Li2, Be2 molecules.
- Effective in capturing static correlation effects.
- Promising approach for improved range-separated DFT calculations.

## Abstract

We introduce an approximation to the short-range correlation energy functional with multide-terminantal 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 vanishing range-separation parameter and the known exact asymptotic expansion at 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.