# Range-separated double-hybrid density-functional theory with coupled-cluster and random-phase approximations

## TL;DR

This paper develops a new range-separated double-hybrid density functional combining coupled-cluster or random-phase approximations with a density functional, improving accuracy for complex molecular interactions with minimal empiricism.

## Contribution

It introduces a novel range-separated double-hybrid scheme incorporating RPA with exchange, enhancing accuracy for challenging molecular systems.

## Key findings

- Improved accuracy for benzene dimer stacking interactions.
- Comparable performance to MP2-based schemes for standard properties.
- Enhanced description of complex molecular interactions.

## Abstract

We construct range-separated double-hybrid schemes which combine coupled-cluster or random-phase approximations with a density functional based on a two-parameter Coulomb-attenuating-method-like decomposition of the electron-electron interaction. We find that the addition of a fraction of short-range electron-electron interaction in the wave-function part of the calculation is globally beneficial for the range-separated double-hybrid scheme involving a variant of the random-phase approximation with exchange terms. Even though the latter scheme is globally as accurate as the corresponding scheme employing only second-order M{{\o}}ller-Plesset perturbation theory for atomization energies, reaction barrier heights, and weak intermolecular interactions of small molecules, it is more accurate for the more complicated case of the benzene dimer in the stacked configuration. The present range-separated double-hybrid scheme employing a random-phase approximation thus represents a new member in the family of double hybrids with minimal empiricism which could be useful for general chemical applications.