# Jellium-with-gap model applied to semilocal kinetic functionals

## TL;DR

This paper introduces a new non-empirical GGA kinetic energy functional based on the jellium-with-gap model, which improves the description of weakly interacting molecular systems in DFT.

## Contribution

It develops a band-gap-dependent gradient expansion and a GGA kinetic energy functional that enhances accuracy for molecular systems.

## Key findings

- Performs well for large atoms
- Accurately describes weakly interacting molecules
- Based on a non-empirical, gap-dependent approach

## Abstract

We investigate a highly-nonlocal generalization of the Lindhard function, given by the jellium-with-gap model. We find a band-gap-dependent gradient expansion of the kinetic energy, which performs noticeably well for large atoms. Using the static linear response theory and the simplest semilocal model for the local band gap, we derive a non-empirical generalized gradient approximation (GGA) of the kinetic energy. This GGA kinetic energy functional is remarkably accurate for the description of weakly interacting molecular systems within the subsystem formulation of Density Functional Theory.