# Improvement of functionals in density functional theory by the inverse Kohn--Sham method and density functional perturbation theory

## TL;DR

This paper introduces a novel approach combining inverse Kohn-Sham and perturbation theory to enhance energy density functionals in density functional theory, achieving accurate reproduction of exchange-correlation functionals and ground-state properties.

## Contribution

It presents a new method to improve energy density functionals by treating their difference as a perturbation, validated through benchmark calculations on noble-gas atoms.

## Key findings

- Reproduced exchange-correlation functionals with high accuracy.
- Achieved precise ground-state energies and densities.
- Validated method on noble-gas atom systems.

## Abstract

We propose a way to improve energy density functionals (EDFs) in the density functional theory based on the combination of the inverse Kohn--Sham method and the density functional perturbation theory. Difference between the known EDF and the exact one is treated as the first-order perturbation. As benchmark calculations, we reproduce the theoretical exchange and correlation functionals in the local density approximation. Systems of noble-gas atoms are used for benchmark calculations, and the ground-state energies and densities, as well as the functionals, are reproduced with good accuracies.