A simple generalized gradient approximation for the noninteracting kinetic energy density functional

A simple, unconventional, nonempirical, constraint-based orbital-free generalized gradient approximation (GGA) noninteracting kinetic energy density functional is presented along with illustrative applications. The innovation is adaptation of constraint-based construction to the essential properties of pseudodensities from the pseudopotentials that are essential in plane-wave-basis ab initio molecular dynamics. This contrasts with constraining to the qualitatively different Kato-cusp-condition densities. The single parameter in the proposed functional is calibrated by satisfying Pauli potential positivity constraints for pseudoatom densities. In static lattice tests on simple metals and semiconductors, the LKT (for the authors' initials) functional outperforms the previous best constraint-based GGA functional, VT84F [Phys. Rev. B 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.