Spin-dependent gradient correction for more accurate atomization energies of molecules

TL;DR

This paper introduces a spin-dependent correction to density functionals that enhances the accuracy of atomization energies in molecules, broadening applicability without compromising other properties.

Contribution

It develops a new density parameter and constructs improved GGAs, zvPBEsol and zvPBEint, with significant accuracy improvements for molecular atomization energies.

Findings

Improved atomization and binding energies for molecules.

Significant (about 30%) accuracy enhancement with meta-GGA correlation functionals.

Maintains original functional performance for other properties.

Abstract

We discuss, simplify, and improve the spin-dependent correction of L.A. Constantin et al., Phys. Rev. B 84, 233103, for atomization energies, and develop a density parameter of the form $v\propto |\nabla n|/n^{10/9}$, found from the statistical ensemble of one-electron densities. The here constructed exchange-correlation generalized gradient approximations (GGAs), named zvPBEsol and zvPBEint, show a broad applicability, and a good accuracy for many applications, because these corrected functionals significantly improve the atomization and binding energies of molecular systems, without worsening the behavior of the original functionals (PBEsol and PBEint) for other properties. This spin-dependent correction is also applied to meta-GGA dynamical correlation functionals combined with exact-exchange; in this case a significant (about 30%) improvement in atomization energies of small molecules is found.