A Simple Generalized Gradient Approximation for the Non-interacting Kinetic Energy Density Functional

TL;DR

This paper introduces a simple, constraint-based GGA kinetic energy functional for orbital-free DFT, calibrated with pseudo-density properties, outperforming previous functionals in tests on metals and semiconductors.

Contribution

A novel, non-empirical GGA kinetic energy functional based on pseudo-density constraints, optimized for plane-wave ab initio molecular dynamics.

Findings

Outperforms previous constraint-based GGA functionals in tests

Is faster and reasonably competitive with parametrized functionals

Shows superior performance in static lattice tests on metals and semiconductors

Abstract

A simple, novel, non-empirical, constraint-based orbital-free generalized gradient approximation (GGA) non-interacting kinetic energy density functional is presented along with illustrative applications. The innovation is adaptation of constraint-based construction to the essential properties of pseudo-densities from the pseudo-potentials that are essential in plane-wave-basis {\it ab initio} molecular dynamics. This contrasts with constraining to the qualitatively different Kato-cusp-condition densities. The single parameter in the new functional is calibrated by satisfying Pauli potential positivity constraints for pseudo-atom densities. In static lattice tests on simple metals and semiconductors, the new LKT functional outperforms the previous best constraint-based GGA functional, VT84F (Phys.\ Rev.\ B \textbf{88}, 161108(R) (2013)), is generally superior to a recently proposed meta-GGA, is reasonably competitive with parametrized two-point functionals, and is substantially faster.