Kinetic energy density functionals from the Airy gas, with an application to the atomization kinetic energies of molecules

TL;DR

This paper develops semilocal kinetic energy density functionals based on the Airy gas model, demonstrating their high accuracy for atomic, molecular, and cluster energies, and revealing their potential to exhibit binding in certain calculations.

Contribution

It introduces new semilocal kinetic energy functionals fitted to the Airy gas, improving accuracy for atomization energies and cluster fragmentation over previous models.

Findings

Most accurate for atomization kinetic energies of molecules

Effective for fragmentation of jellium clusters

Can exhibit binding in spin unrestricted calculations

Abstract

We construct and study several semilocal density functional approximations for the positive Kohn-Sham kinetic energy density. These functionals fit the kinetic energy density of the Airy gas and they can be accurate for integrated kinetic energies of atoms, molecules, jellium clusters and jellium surfaces. We find that these functionals are the most accurate ones for atomization kinetic energies of molecules and for fragmentation of jellium clusters. We also report that local and semilocal kinetic energy functionals can show "binding" when the density of a spin unrestricted Kohn-Sham calculation is used.