# Simple fully non-local density functionals for the electronic repulsion energy

## TL;DR

This paper introduces a fully non-local, self-interaction free density functional for electronic repulsion energy that accurately captures strong correlation effects and asymptotic behavior, surpassing standard DFT limitations.

## Contribution

It presents a novel non-local functional based on the strong coupling limit, capable of modeling strong correlation effects without error cancellation, advancing beyond Jacob's ladder.

## Key findings

- Captures strong correlation effects in bond dissociation
- Yields energy densities with correct asymptotic behavior
- Removes self-interaction errors

## Abstract

From a simplified version of the mathematical structure of the strong coupling limit of the exact exchange-correlation functional, we construct an approximation for the electronic repulsion energy at physical coupling strength, which is fully non-local. This functional is self-interaction free and yields energy densities within the definition of the electrostatic potential of the exchange-correlation hole that are locally accurate and have the correct asymptotic behavior. The model is able to capture strong correlation effects that arise from chemical bond dissociation, without relying on error cancellation. These features, which are usually missed by standard DFT functionals, are captured by the highly nonlocal structure, which goes beyond the Jacob's ladder framework for functional construction, by using integrals of the density as the key ingredient. Possible routes for obtaining the full exchange-correlation functional by recovering the missing kinetic component of the correlation energy are also implemented and discussed.