Increasing physical constraints and improving performances in a parameter-free GGA functional

In this Letter we present an evolution of the TCA functional V. Tognetti, P. Cortona, C. Adamo, J. Chem. Phys. 128 (2008) 034101] that gives a vanishing correlation energy for hydrogenoid atoms. This feature of the exact functional is incorporated in the TCA approximation at the generalized-gradient level, without kinetic energy density or higher order density derivatives dependence. A significant improvement of atomic and atomization energies, activation barriers and ionization potentials is found when the new correlation is coupled with modified PBE exchange functionals, while structural parameters are close in accuracy to those provided by the original PBE functional.