Analysis of the kinetic energy functional in the generalized gradient approximation

• Published in: The Journal of chemical physics 2021-02, Vol.154 (8), p.084107-084107
• Main Authors: Francisco, Héctor I., Carmona-Espíndola, Javier, Gázquez, José L.
• Format: Article
• Language: English
• Subjects: Approximation; Energy; Flux density; Infinity; Interpolation; Kinetic energy; Mathematical analysis
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/5.0040973

A new density functional for the total kinetic energy in the generalized gradient approximation is developed through an enhancement factor that leads to the correct behavior in the limits when the reduced density gradient tends to 0 and to infinity and by making use of the conjoint conjecture for the interpolation between these two limits, through the incorporation, in the intermediate region of constraints that are associated with the exchange energy functional. The resulting functional leads to a reasonable description of the kinetic energies of atoms and molecules when it is used in combination with Hartree–Fock densities. Additionally, in order to improve the behavior of the kinetic energy density, a new enhancement factor for the Pauli kinetic energy is proposed by incorporating the correct behavior into the limits when the reduced density gradient tends to 0 and to infinity, together with the positivity condition, and imposing through the interpolation function that the sum of its integral over the whole space and the Weiszacker energy must be equal to the value obtained with the enhancement factor developed for the total kinetic energy.